8 ms·

Most cancer screenings don’t extend life, study finds

69 points by geeB 3y ago

deleted 3y ago
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kccqzy 3y ago
This is the pertinent quote: > “Cancer screening was never really designed to increase longevity. Screenings are really designed to decrease premature deaths from cancer.” Explained another way, Dahut said, if a person’s life expectancy at birth was 80, a cancer screening may prevent their premature death at 65, but it wouldn’t necessarily mean they’d live to be 90 instead of the predicted 80. Personally I think this is just a matter of terminology in public health not necessarily aligning with our intuitive understanding. I presume most people would think that preventing a shortening of lifespan is prolonging your life, but the article makes clear that they are different.
- ekanes 3y ago
  So they increase your lifespan probabilistically, but not in any terms you can measure. That said, the article's points about the costs of screening is valid and interesting. False negatives, false positives, time and money, those are absolutely real costs and worth taking into account.
- Clent 3y ago
  They are conflating cancer survival rates with longevity. When has someone claimed that treating cancer would increase life expectancy above the average? This is a dangerous article. People don't need more reasons to avoid cancer screenings.
  - amanaplanacanal 3y ago
    It looks like they were comparing a group that got screening vs a group that didn’t get screening. If the group that got screening didn’t live longer than the group that didn’t get screening, that seems like a lot of wasted dollars.
    - throwway120385 3y ago
      Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die. What if some people in the group that didn't get screening had fewer high-quality years? It might simply be that the last 5 years of life for people who are screened positive early on and who subsequently receive treatment is a better 5 years than the last 5 years of life for people who aren't screened positive early on and who subsequently have to undergo brutal hail mary treatments at the last minute.
      - pessimizer 3y ago
        > Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die. Claiming that there are missing elements that could possibly turn the equation in favor of screening is cause for further research and analysis. You can't just claim that they fall in your favor; some diagnostic and exploratory processes due to false positives are painful and/or dangerous in and of themselves. > What if "What if" is right. You can't just conjure these people into existence to justify current policies, you have to find them and do the statistics.
        throwway120385 3y ago
        Given that screening is arguably benign for most people, you could argue that we continue screening while we gather more information. But you do whatever you want to do. I'm just pointing out that it's really premature to cancel all of your screenings based on the idea that it doesn't add any years to your life. That may be true, but there's more to a life than how long you live.
        idopmstuff 3y ago
        > Given that screening is arguably benign for most people You're 100% wrong here, this is not a given. Prostate cancer screenings, which are very common, can have both false positives as well as findings of cancer that is and would remain completely benign. These can both lead to unnecessary treatments that cause serious negative health effects, including incontinence and erectile dysfunction. https://www.cdc.gov/cancer/prostate/basic_info/benefits-harms.htm https://www.cdc.gov/cancer/prostate/basic_info/benefits-harm...
  - rdedev 3y ago
    I think the consensus on cancer screening is stil not fully there? Came across this video by a cardiologist a long time ago https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p I guess the main gist is that screening is not completely benign and a positive screen might lead to more interventions for what in the end could just be a benign tumor. Then there's the other point of detecting it late in life. Like treatment for cancer might not make much sense if you are already 89 years old
    - haltingproblem 3y ago
      This is the negative expectation part of most medical screening that most analyses miss. - Medical screenings themselves have iatrogenic effects, - the false positives interventions resulting from screenings have further negative effects and - finally the true positive interventions don't necessarily prolong life. All in all very difficult (confounding) tradeoffs that are impossible to quantify and understand especially when the cultural pressure is to do something.
      - arisAlexis 3y ago
        Do you really believe your third point? That most medical interventions for cancer do not prolong life? Or the word necessarily means your argument is null like "not all interventions prolong life". Yeah , we knew that already. It's never 100%.
        NoZebra120vClip 3y ago
        I'd rather die of cancer than die of chemotherapy.
        newaccount74 3y ago
        A friend of mine had a pretty agressive cancer at age 16. He suffered through chemotherapy, a bone marrow transplant, and another round of chemo a year later. I think it sucked pretty bad. I visited him once in hospital, they made me wear a full body suit to prevent any infections. But that was 20 years ago. He lives a normal life now and has a family. I'm pretty sure chemo was worth it.
  - aeturnum 3y ago
    Why would it be dangerous for people to avoid cancer screenings if those screenings do not impact life expectancy? You might want to know if you have cancer, but doesn't this suggest that...there's no baseline argument to suggest that all people undergo those screenings?
    - arisAlexis 3y ago
      They do impact life expectancy. The English language is a bit confusing to some mixed with statistics. They do not make life greater than average but they do make you closer to the average than if you die earlier.
- glimshe 3y ago
  If we are avoiding premature deaths for a subset of the population, wouldn't that by definition increase average life expectancy?
- orblivion 3y ago
  I mean, you could interpret that as "most cancer screenings don't extend life, because they come back negative". It's the "not most" case you're testing for in the first place.
  - pessimizer 3y ago
    Not all positive tests are cancer. In some cases, actual cancers could be a tiny minority of positive tests. The tests themselves are a dangerous tool, and the way we minimize that danger is through statistics.
    - kccqzy 3y ago
      Then you are just changing one form of bad communication with another form. When a test indicates that there is cancer, the physician is not supposed to say "you have cancer" but rather "there is X% probability that you have cancer." If the test comes back negative, it should be "there is Y% probability that you have cancer" where presumably Y<X.
- somenameforme 3y ago
  The paper [1] is more well written and clear than the CNN article. They were comparing the aggregate life expectancies of people who went through regular screenings vs those who did not, and there was near zero difference except for colorectal screenings where the difference was about 4 months of difference. The paper is indeed presenting strong evidence that regular screenings have minimal value. [1] - https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2808648 https://jamanetwork.com/journals/jamainternalmedicine/fullar...
  - hn_throwaway_99 3y ago
    Thanks for posting that. I read the article but not the paper, but I still feel like this may be a case where scientists "treat all time equally" in a way that most people do not, resulting in differing conclusions even though the data is the same. That is, putting aside monetary costs for the moment (which I know is not a good idea in reality, but want to focus on another issue), you often hear about how false positives cause "added anxiety and unnecessary treatments, which can cause harm", but if a breast cancer screening saves, say, lets one woman live until 80 instead of dying at 40, how many other people's "added anxiety" would it take to say "OK, that test was worth it". I think a lot of folks would go think that saving that life should be valued a lot more than just, say, comparing 40 years for her vs. time/anxiety "wasted" for false positives.
    - vc8f6vVV 3y ago
      X-ray is not just adding anxiety, it's harmful, and it's affecting all women who get screening, not only those who actually get cancer. Magic of numbers.
  - francisofascii 3y ago
    > except for colorectal screenings where the difference was about 4 months of difference That sounds, uh, significant. So to clarify, does that mean people gain 4 months on average by getting this screening? Those who get the cancer gain years, and those that don't gain 0, so the average is 4 months?
- kazinator 3y ago
  If we decrease premature deaths from any cause, particularly a common cause of premature deaths, we increase life expectancy. Or just what do the authors think life expectancy means? It's an average. Every premature death drags down average life expectancy. If we say that cancer screening has no effect of life expectancy, that's exactly the same as saying that it doesn't prevent premature deaths. If cancer screening effectively prevents premature deaths, but the effect on the population's life expectancy is small, that effect is the wrong thing to be focusing on, potentially resulting in a harmful takeaway message.
  - LorenPechtel 3y ago
    No, because we might be replacing one cause with another. That's what they've found with PSA--it kills (via treating things that wouldn't actually have killed the patient) as many as it saves.
    - kazinator 3y ago
      > That's what they've found with PSA--it kills (via treating things ...) I'm not sure what PSA you're referring to. The Prostate-Specific Antigen PSA is something secreted by the body, and not a treatment, so it can't be that one. Are you referring to overdiagnosis (via PSA or any other screening), resulting in overtreatment?
      - LorenPechtel 3y ago
        PSA is also commonly used to refer to the test that measures the PSA level. And, yes, it's treatment of things that weren't actually going to kill the patient. It's been known for quite a while that doing the test for screening produces no increase in life expectancy. What this study is saying is that the same problem seems to apply to most other cancer screenings.
  - vc8f6vVV 3y ago
    You may be decreasing premature deaths from cancer but increasing premature deaths from other causes related to screening, thus you don't increase life expectancy. Read the original article in JAMA.
- raverbashing 3y ago
  Then the way this is being divulged is absolutely a very bad way Yes, life expectancy should count premature deaths Saying it "doesn't extend live" goes against that, because it absolutely does increase life expectancy Science communication is bad
- teleforce 3y ago
  There's only two things that are certain in this world, death and taxes - Benjamin Franklin. The main purpose of screening for early disease or genetic condition detection regardless of the diseases or illness, cancer, heart attack, stroke, etc, is not really to prolong longevity, even though that's a wonderful side effect, but the main thing to prevent complication(s) that may arise from the late detection. Apparently death does not incurs extra and massive medical bills, on the other hand complications will certainly do. If you connect the dots, this suddenly become a really good and plausible conspiracy theory. It's a shame that most of the health organizations, I'm looking at you American Heart Association (AHA), are really against any form of routine screening [1],[2]. [1] American Heart Association 14-Element Screening (Maron, BJ Circulation 2014): https://med.stanford.edu/content/dam/sm/ppc/documents/HSupervision/AHA_14-point.pdf https://med.stanford.edu/content/dam/sm/ppc/documents/HSuper... [2] ACC/AHA Release Recommendations For Congenital and Genetic Heart Disease Screenings in Youth: https://www.acc.org/latest-in-cardiology/articles/2014/09/15/14/24/acc-aha-release-recommendations-for-congenital-and-genetic-heart-disease-screenings-in-youth https://www.acc.org/latest-in-cardiology/articles/2014/09/15...
  - vc8f6vVV 3y ago
    Just curious, have you read the original article in JAMA?
- vc8f6vVV 3y ago
  Have you read the original article, not the CNN interpretation? They are talking about harm vs benefits of screening. In simple words: you performed colonoscopy, got colon perforation and died of complications. Was colon cancer prevented? Absolutely! You didn't die of colon cancer! Is it any easier? No, it's not. The chance of dying of breast cancer is around 2.5%, so 1 women in 39 will die from that. OTOH annual X-rays affect the other 38 too, how many of them will die from X-ray exposure (which can cause e.g. another type of cancer, not necessary breast)? For the sake of discussion let's say 1 in 380. Congratulations, you've just increased breast cancer related death by 10%! Only it won't be in statistic as deaths from breast cancer.
chipsrafferty 3y ago
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monero-xmr 3y ago
An excellent episode of EconTalk came out today on this very subject: Open: https://simplecast.econtalk.org/episodes/vinay-prasad-on-cancer-screening https://simplecast.econtalk.org/episodes/vinay-prasad-on-can... Apple: https://podcasts.apple.com/us/podcast/econtalk/id135066958?i=1000625920965 https://podcasts.apple.com/us/podcast/econtalk/id135066958?i... Highly recommend the episode and show. The gist is that cancer is only 4% of deaths, and screening only reduces those 4% by 20% (so it does not help whatsoever 80% of cancers). But there is a lot more to the episode. The most important thing you need to do to prevent early death is reduce heart attack and stroke, and that requires better diet and exercise. Really the best drug of all is diet and exercise.
- kiba 3y ago
  Exercise also reduces cancer risk.
- Retric 3y ago
  Those numbers seem really off. The US has 3,464,231 deaths per year with cancer killing just over 600k, so 17.3%. https://www.cdc.gov/nchs/fastats/deaths.htm https://www.cdc.gov/nchs/fastats/deaths.htm https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/cancer-facts-figures-2021.html https://www.cancer.org/research/cancer-facts-statistics/all-... Also cancer screenings happen in the US. Thus 750k deaths without screenings and 80% of that = 600k deaths with screenings and 150k deaths postponed. Are they using some unusual definition or something?
  - rocmcd 3y ago
    The 4% GP quoted was in reference to individual cancers (since there is no "cancer" screening, each screening is specific to a type of cancer). I'm having trouble finding numbers, but the comment by Vinay was basically saying that each screening is testing for something that has 1-4% chance of killing you. Not that 4% of all cause mortality is cancer, which is incorrect. In the context of individual screenings per cancer, the numbers roughly make sense based on what I could find, but I am by no means an expert. The specific video/content they are rehashing is the one by Vinay here - https://www.youtube.com/watch?v=-9hQO7X1bmU https://www.youtube.com/watch?v=-9hQO7X1bmU I'd highly recommend listening to the Econtalk conversation as there is a lot of nuance behind why screenings (at least as they are done today) could potentially be a net negative at the individual level and don't seem to have improved all-cause mortality in a significant way (according to Vinay).
twoodfin 3y ago
I am skeptical of the implied lesson of this analysis—and it is a meta-analysis of other research, not an original study. Just take as given that the analysis is correct, and screening for rare Disease A on net has no effect on life expectancy. Almost no one actually gets Disease A, but everyone is screened for it, and that has some diffuse cost to life expectancy: Screen enough people enough times and someone will die in a car accident on the way to or from the doctor's office. More likely the screening crowds out other more net-beneficial medical testing or is taken as some false comfort to continue an unhealthy lifestyle. Modern cancer treatment, especially for the most common types (i.e. the most likely to be screened for) is very good, even if the cancer is caught later due to lack of screening. So even the folks who catch it early due to screening don't incur a benefit in many cases, further pushing down the life-expectancy win on average. Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome. If you're a public health authority in a utilitarian and budget-constrained mindset, sure, don't encourage screenings by the logic and findings of this analysis. But I don't think individuals should consider on-average-LE-negative screenings as something to avoid.
- circlefavshape 3y ago
  > Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome. I'd say this depends on the nature of the diffuse negative effects you mention - if it's car accidents on the way to the doctor's office that's one thing, but if it's people dying during surgery they actually didn't need that's another
- pajep 3y ago
  what are some cancer screening that one should actively pursue?
  - SpaceManNabs 3y ago
    Speak with your doctor about this, especially because I am not one, but from what I understand, the ones that you have a family history for, are pre-diposed by environment, the common ones, and the ones caught by usual body checks / tests during check ups. Again, not giving advice but things you can start a conversation with your doctor with.
kazinator 3y ago
> But experts say this doesn’t mean you should cancel that colonoscopy or mammogram appointment. That can only be that these experts disagree with the study, because if it were properly conducted such that its findings are true, then in fact its conclusions do add up to skipping colonoscopies and mammograms. The study is saying that the diagnostic procedures have no effect on outcome. You should not waste time on procedures that don't change outcome.
- hedora 3y ago
  The article dismisses a population-wide life expectancy increase of 4 months from one of the screens. If that's your bar, then most preventative screening is probably not worthwhile.
  - kazinator 3y ago
    If, say, only 5% of the people undertake that screening and manage to bring up the population expectancy by four months, then the actual effect could be over six years for screened individuals. It's pretty dishonest to be confusing the effect of screening by counting unscreened individuals. It's like claiming that seat belts don't work by looking only at fatality figures that don't inform to what extent seatbelts were worn.
  - wnissen 3y ago
    It would really help me to use the same methodology but compare it to people smoking like they did in the 1980s.
retrocryptid 3y ago
Wow. People really are bad at reasoning about probabilities. A more important question might be "does not getting cancer treatments lead to a shortened lifespan?" And that is exactly the question they did not ask in that study.
aydyn 3y ago
> explained that if breast cancer caused 3% of all female deaths and screenings reduced these deaths by 35%, that’s a good result on its own. But screenings may change mortality overall by only about 1% This statement makes it clear what's going on. In ML terms: class imbalance. 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. It won't make any statistical difference in overall population survival. But for the 0.1%? It will save their lives.
- hedora 3y ago
  Yes, and if you perform dozens of tests per year on the general population, and take action based on the results, then the probabilities add up pretty rapidly.
- ilya_m 3y ago
  I understand the comment's thesis, but I'd like to see more accurate numbers used where real health outcomes are concerned. The lifetime risk of being diagnosed with colorectal cancer is ~4%. (With the odds trending higher for the younger generation.) The risk of _death_ from this cancer is ~1%.
- vc8f6vVV 3y ago
  > 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. But they may have complications from a colonoscopy, that's the idea. No test is completely harmless, even a blood work. You save some lives but may loose others, that's the point of the paper. And of course you waste resources that can be used to find a cure.
apsec112 3y ago
Me before reading: "this study, like ~every study, will detect no effect on all-cause mortality because that needs a crazy big sample size" After reading: "this study, like ~every study, detected no effect on all-cause mortality because that needs a crazy big sample size" A three-year study where one group magically had zero car crashes would need a sample size of 5,000,000 to detect a difference in all-cause mortality. It's really hard. (80% chance of p < 0.05)
- hedora 3y ago
  They actually did show an improvement of all-cause mortality for one of the screens (corresponding to a 4 month increase in life expectancy), and "insignificant" improvements in others. (The headline is probably technically true, but I think it is intentionally misleading and disingenuous.)
- deleted 3y ago
  [deleted]
hedora 3y ago
This article uses extremely contorted logic. Pretty much all health care has some cost, and hopefully some benefit in terms of life expectancy and/or quality-of-life-adjusted life expectancy. If you assume all the costs are fungible, then the analysis is straightforward (the costs are not actually fungible -- some things cost money, other things cost patient time, or use resources that are in finite supply -- so it turns into a linear programming problem, and we've been able to solve those since before computers existed). With fungible costs, for each of the available health care services, you the expected increase of life expectancy and divide it by the cost, and prioritize the things that have the highest benefit/cost ratio. The article doesn't talk at all about the cost of the screens, which is fairly low (vs. spending time exercising, or a year of exotic chemo). It also doesn't look at patient quality of life.
wkat4242 3y ago
Still it's nice to be the one outlier. For those with higher risk it would still be a good idea. Smokers, people who work with chemicals etc.
neongodzilla 3y ago
Sounds like a talking point one would use if you no longer wanted to provide coverage for preventive care.
deleted 3y ago
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porcoda 3y ago
(Note: very US centric comment here) I’ve become skeptical of the motives behind any article that seems to seed some level of doubt about health screenings and any preventative or treatment measure that involves the healthcare system itself. They always stink of the insurance and for-profit healthcare system and their aversion to paying anything out beyond the absolute bare minimum to get people the care they need. I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven.
- highwayman47 3y ago
  Ya exactly, I’ve had 2 family members catch pancreatic cancer early and be cured. It’s typically the most fatal cancer.
  - DonsDiscountGas 3y ago
    This study did not look at pancreatic cancer.
- DonsDiscountGas 3y ago
  I can see why insurance companies might not want to pay, but the people selling the screenings absolutely would want you to get screened. I dunno about all types of cancer (and screening methods), but mammograms definitely are not helpful and this has been known for a long time [0] [0] https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagnosis https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagn... (2015)
- andrekandre 3y ago
  > I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven. in japan some prefectures or cities will send you leaflets/guides about how to get prescreening for cancer markers and early treatment for people past a certain age i seem to also remember seeing they offer incentives like first screening only 700 yen (about 5 bucks) etc so, yea, different systems, different incentives i guess
- 3y ago
amluto 3y ago
The actual study is (after some URL sanitization): https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2808648 https://jamanetwork.com/journals/jamainternalmedicine/fullar... and I do not like it. It suffers from what I consider an extremely common problem in statistics: if you define the question poorly, then your output is garbage no matter how fancy or careful your analysis is. We can start with the beginning of the abstract: > Importance Cancer screening tests are promoted to save life by increasing longevity, but it is unknown whether people will live longer with commonly used cancer screening tests. I have never heard of a doctor suggesting a cancer screening by saying "this might save your life by increasing your longevity." What does that even mean? So let's try to figure it out. The paper uses the terms "lifetime" and "longevity" somewhat interchangeably, and it does not define either term. The best I can figure out is that, for an individual deceased person, they have a certain lifetime in days from when they were screened to when they because deceased. (Or a certain lifetime in days from birth to death, and I'm not sure this distinction matters.) Great, but this is only for one patient. What about for a sample of patients or for a population in general or for the probability distribution of lifetimes of a given patient conditioned on whether they do or do not get screened? The article does not say, and a single "lifetime" number is not a probability distribution. Is it an expected value or a mean? A median? A mode? No comment. One of the headline conclusions is: > Based on the observed relative risks for all-cause mortality and the reported follow-up time in the trials, the only screening test that significantly increased longevity was sigmoidoscopy, by 110 days (95% CI, 0-274 days) (Table 2, Figure 2) Figure 2 is useless. Table 2 is somewhat informative, and it has a column for relative risk of all-cause mortality and a column for lifetime gained and its 95% CI. But WAIT A MOMENT! The only way you can know the lifetime of an individual patient is if they're dead. If they're dead, their risk of all-cause mortality by the time they died is 100%. That's not 100% plus or minus something with some relative risk thrown in -- they are dead enough to have a date of death so that someone could compute their lifetime! Or maybe "lifetime" means something else, and the authors didn't bother to figure it out and say what they meant. So what exactly is this paper even analyzing? So I suspect this is a meta-analysis of studies, of which some may or may not have been high enough quality to define their terms, and probably several of which used "lifetime" to mean some estimated property of a distribution, and this meta-analysis completely failed to figure out what the included studies were talking about. So I rate this meta-analysis as almost entirely useless, on account of it failing to actually analyze anything that makes sense. So I don't think any conclusions can be drawn. Although... ACS puts the lifetime risk of colorectal cancer at 1:25 or so. So one might naively translate a 110-day lifetime extension for everyone to a 110 day · 25 = 2750 day = ~7.5 year expected lifetime extension for people who actually get colorectal cancer. Sign me up -- 7.5 more expected years of life and presumably more than that of quality life years in the event I contract a not-particularly-rare disease sounds like a pretty good deal. (Colorectal cancer screening is not all that unpleasant, and I apparently only have a 96% chance of the screening being unnecessary.)
arisAlexis 3y ago
These articles are dangerous for the public. They may not go to have their regular checkups that will make them die younger and thus ironically yeah their life would not be extended any more.
dang 3y ago
Recent and related: The real cost of a preventive health scan goes well beyond the price tag - https://news.ycombinator.com/item?id=37266189 https://news.ycombinator.com/item?id=37266189 - Aug 2023 (254 comments)
arisAlexis 3y ago
There is a really weird connotation with this: if when malignancy is found and then actions are taken and when it's found earlier actions are taken earlier but they still don't survive means that when you treat a cancer early is the same as treating it late. But that is contrary to all studies ever done. So either there is some mistake or stage I with stage 3 cancer have the same survival. Look like someone fucked up some math imo.
- michael1999 3y ago
  It could also mean there are other negative forces balancing out the positive forces. Negative outcomes for broad screening include. - Early testing means more visits to the hospitals/clinics. Those are famously dangerous places to get sick. - False positives mean unneeded treatment. That can shorten your life. - Finding things earlier also means earlier treatment. That can kill you. Every trip to a hospital means a non-zero risk of catching MRSA and other nasties. - Some things would be handled by the immune system anyway. The treatment might provide no benefit over an ignorant outcome. I also find it easy to believe that among all the oncologists and hospitals, some of them might be at best neutral, or even net-negative in mortality and morbidity. This is about the whole population, not just leading units at famous hospitals. There are doctors out there with the ethics of a bent mechanic.
Flatcircle 3y ago
Breast cancer screens def save lives. Can't speak to all screenings but some def work.
- flarg 3y ago
  Evidence?
  - haldujai 3y ago
    It's unequivocal that screening reduces breast-cancer specific mortality. None of the studies are powered enough to draw a positive or negative conclusion for overall mortality. The second last link is an explanation of why this is the case, where we're at and what the implications are. The last link explains the NCCN rationale and decision making process. http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b026a29-1.pdf http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b02... https://www.nejm.org/doi/full/10.1056/nejmoa1000727 https://www.nejm.org/doi/full/10.1056/nejmoa1000727 https://academic.oup.com/jnci/article/106/11/dju261/1496367?login=true https://academic.oup.com/jnci/article/106/11/dju261/1496367?... https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xml?print https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xm...
- giarc 3y ago
  "mammography screening did not prolong life" from the abstract. If you are unfortunately talking about a personal experience, sorry, but you can't confuse n=1 stories with large research studies.
- teuobk 3y ago
  Except breast cancer screening, at least via mammography, doesn't save lives. See, for example: https://thennt.com/nnt/screening-mammography-for-reducing-deaths/ https://thennt.com/nnt/screening-mammography-for-reducing-de...
  - bironran 3y ago
jbandela1 3y ago
What surprising to me is that sigmoidoscopy shows a benefit but colonoscopy doesn’t. In colonoscopy, the entire colon is examined by using a long flexible tube. In sigmoidoscopy, only the lower portion of the colon is checked, again by using a flexible tube. The things that come to mind is that sigmoidoscopy may be better tolerated by patients or have fewer complications.
- giarc 3y ago
  Likely that the cancers found by the sigmoid are the ones that reduce life years. Perhaps the cancers that are found and treated higher up the colon would have been found out in other ways or not serious enough? I'm not a doctor, so not sure.
  - psychphysic 3y ago
    Indeed there are dramatic differences between ascending and descending colon cancers. They are also dissimilar in their chances of presenting early with symptoms making screening less useful vs those that don't present early. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/
kwhitefoot 3y ago
The patient is not interested in the effect on the average life expectancy of all people in society, they are only interested in their own case when they are diagnosed early enough to have treatment that will extend their life if they have cancer. This is a different sub-population.
- haldujai 3y ago
  That's not the criteria for population level interventions. This is to answer the question of whether should the USPSTF make a positive recommendation and force insurers to pay or if public health systems should adopt this. You're conflating this with individual patient decisions.
memonkey 3y ago
What's the next question then? Curious to know if any of these screening caught cancers at various stages and if there is a correlation to better long term prognosis.
psychphysic 3y ago
This is not an unexpected result. Last I checked breast self examination also does not reduce deaths from breast cancer, nor testicular self examination. If anyone's interested the "Wilson criteria" is the basis of decisions about screening programmes and many run programmes fail it.
stevehawk 3y ago
Is this study just proving that other things kill you while you're being or after you've been treated for cancer?
- trgn 3y ago
  It provides evidence that a diagnostic approach to healthcare misunderstands that good health is a complex expression of a million factors, and not a function of the number of healthcare interventions. A diagnostic approach to healthcare can be easily bureaucratized (come collect your stamp after your colonoscopy!). A touchy-feely "million factors" approach cannot.
- csours 3y ago
  Someone else linked to https://thennt.com/nnt/screening-mammography-for-reducing-deaths/ https://thennt.com/nnt/screening-mammography-for-reducing-de... Quote: > "Two recent data reviews deserve further mention. The United Kingdom commissioned an independent review after dissenting voices swelled, for the purpose of better informing shared decision making and educational materials about the harms and benefits of screening.6 Unfortunately the review concluded that screening mammography trials were inadequately powered to detect an impact on all-cause mortality, and therefore used breast cancer mortality as a primary outcome. They concluded a 20% reduction and used this in their discussion of harms and benefits. As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether). Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed." > "They concluded a 20% reduction and used this in their discussion of harms and benefits." We want to do things that will help people. On an individual level, people have the right to make decisions for themselves. At the population level, we should do things that can be proven to be helpful. This leads to decisions that feel heartless - denying people a vaccine during a deadly pandemic while it is being tested; delaying or denying introduction of a new medicine that shows only marginal improvements over an old one. So their independent review showed benefit by changing the criteria for comparison. We want to help people, and medical interventions feel like helping. Unfortunately, sometimes they can be the equivalent of The Politician's Fallacy: "There was a problem. I did something about the problem. Therefore the problem is fixed" > "As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether)." People die of /something/. That thing becomes a target to fix; and we deploy resources to fix it. We become emotionally connected to some interventions. (Speaking personally, I'm participating in a bike ride in a few weeks to raise money for breast cancer screenings.) Some of those resources are beneficial, some are not, some may be harmful. > "Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."
bironran 3y ago
Does that mean early cancer treatments don't prolong life? Positive screening result usually leads to treatment of one kind or another. Without screening, treatment would start later, if at all. Is that a corollary of this study?
michael1999 3y ago
discussed here - https://news.ycombinator.com/item?id=37296122 https://news.ycombinator.com/item?id=37296122 I found this comment useful: - https://news.ycombinator.com/item?id=37297963 https://news.ycombinator.com/item?id=37297963 Several comments noted that a 4 month improvement in life expectancy (for sigmoidoscopy) over the whole population is actually pretty good for a low-incidence cancer. That's several years for the people who actually get it. But the comments seem naive about the downsides of broad screening: over-treatment, iatrogenic disease, false positives, opportunity cost, etc.
- dang 3y ago
  (this comment was originally posted to https://news.ycombinator.com/item?id=37312540 https://news.ycombinator.com/item?id=37312540, but we've merged that thread hither. that's why the comment links to its own thread now)
0cf8612b2e1e 3y ago
> In this systematic review and meta-analysis of 18 long-term randomized clinical trials involving 2.1 million individuals, colorectal cancer screening with sigmoidoscopy prolonged lifetime by 110 days, while fecal testing and mammography screening did not prolong life… That is shockingly bad. An extra three months of life is not nothing, but not exactly a clear win to push people towards the added stress and effort to be screened.
- op00to 3y ago
  What about quality of life? Colon cancer did not kill my wife's Grandma, but complications of the surgery did.
freedude 3y ago
My wife's grandpa was diagnosed with prostate cancer. He was 82 and had been a natural food store owner for over 30 years. He said the side effects to the treatment and the surgery was too great for him to endure and would impede his quality of life. He passed away 4 years later from pneumonia unrelated to the cancer. The cancer wasn't easy to deal with in those four years. He wasn't cut up and on chemo or radiation either. I agree with him in that too much can be "done"
xp84 3y ago
I am still disturbed by this though. The alternative I see to "get screenings" is "get no screenings." If you're one of the ones who actually do have an aggressive cancer, and you don't find out about it until it's like Stage Four, then you just definitely die, badly and soon. You, specifically, might have been helped if screened when you had a little baby tumor. So, while I see the "statistically" part, asking everyone to get zero screenings until you start coughing up blood (or whatever happens when the cancer starts showing very obvious signs)... it just seems weird on the individual level. Nobody knows (nor can they know) if you're the person who would be cured with treatment, or if you're the person whose outcome wouldn't have changed a bit with treatment (for better or for worse). That question matters individually, and while "statistically you're slightly more likely to be in the second group" according to these studies, that doesn't make me feel great about just declining all screenings.
- vc8f6vVV 3y ago
  > You, specifically, might have been helped if screened when you had a little baby tumor. Or your screening might have caused that tumor? X-rays are not harmless and they can cause cancer. Other screenings have their respective complications. Aren't you disturbed by a thought that maybe you wouldn't have any cancer if not for screening? Or you would have a healthy colon if not for the intern who perforated it during colonoscopy?

69 points by geeB 3y ago

deleted 3y ago

[deleted]

This is the pertinent quote: > “Cancer screening was never really designed to increase longevity. Screenings are really designed to decrease premature deaths from cancer.” Explained another way, Dahut said, if a person’s life expectancy at birth was 80, a cancer screening may prevent their premature death at 65, but it wouldn’t necessarily mean they’d live to be 90 instead of the predicted 80. Personally I think this is just a matter of terminology in public health not necessarily aligning with our intuitive understanding. I presume most people would think that preventing a shortening of lifespan is prolonging your life, but the article makes clear that they are different.

ekanes 3y ago
So they increase your lifespan probabilistically, but not in any terms you can measure. That said, the article's points about the costs of screening is valid and interesting. False negatives, false positives, time and money, those are absolutely real costs and worth taking into account.
Clent 3y ago
They are conflating cancer survival rates with longevity. When has someone claimed that treating cancer would increase life expectancy above the average? This is a dangerous article. People don't need more reasons to avoid cancer screenings.
- amanaplanacanal 3y ago
  It looks like they were comparing a group that got screening vs a group that didn’t get screening. If the group that got screening didn’t live longer than the group that didn’t get screening, that seems like a lot of wasted dollars.
  - throwway120385 3y ago
    Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die. What if some people in the group that didn't get screening had fewer high-quality years? It might simply be that the last 5 years of life for people who are screened positive early on and who subsequently receive treatment is a better 5 years than the last 5 years of life for people who aren't screened positive early on and who subsequently have to undergo brutal hail mary treatments at the last minute.
    - pessimizer 3y ago
      > Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die. Claiming that there are missing elements that could possibly turn the equation in favor of screening is cause for further research and analysis. You can't just claim that they fall in your favor; some diagnostic and exploratory processes due to false positives are painful and/or dangerous in and of themselves. > What if "What if" is right. You can't just conjure these people into existence to justify current policies, you have to find them and do the statistics.
      - throwway120385 3y ago
        Given that screening is arguably benign for most people, you could argue that we continue screening while we gather more information. But you do whatever you want to do. I'm just pointing out that it's really premature to cancel all of your screenings based on the idea that it doesn't add any years to your life. That may be true, but there's more to a life than how long you live.
        idopmstuff 3y ago
        > Given that screening is arguably benign for most people You're 100% wrong here, this is not a given. Prostate cancer screenings, which are very common, can have both false positives as well as findings of cancer that is and would remain completely benign. These can both lead to unnecessary treatments that cause serious negative health effects, including incontinence and erectile dysfunction. https://www.cdc.gov/cancer/prostate/basic_info/benefits-harms.htm https://www.cdc.gov/cancer/prostate/basic_info/benefits-harm...
- rdedev 3y ago
  I think the consensus on cancer screening is stil not fully there? Came across this video by a cardiologist a long time ago https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p I guess the main gist is that screening is not completely benign and a positive screen might lead to more interventions for what in the end could just be a benign tumor. Then there's the other point of detecting it late in life. Like treatment for cancer might not make much sense if you are already 89 years old
  - haltingproblem 3y ago
    This is the negative expectation part of most medical screening that most analyses miss. - Medical screenings themselves have iatrogenic effects, - the false positives interventions resulting from screenings have further negative effects and - finally the true positive interventions don't necessarily prolong life. All in all very difficult (confounding) tradeoffs that are impossible to quantify and understand especially when the cultural pressure is to do something.
    - arisAlexis 3y ago
      Do you really believe your third point? That most medical interventions for cancer do not prolong life? Or the word necessarily means your argument is null like "not all interventions prolong life". Yeah , we knew that already. It's never 100%.
      - NoZebra120vClip 3y ago
        I'd rather die of cancer than die of chemotherapy.
        newaccount74 3y ago
        A friend of mine had a pretty agressive cancer at age 16. He suffered through chemotherapy, a bone marrow transplant, and another round of chemo a year later. I think it sucked pretty bad. I visited him once in hospital, they made me wear a full body suit to prevent any infections. But that was 20 years ago. He lives a normal life now and has a family. I'm pretty sure chemo was worth it.
- aeturnum 3y ago
  Why would it be dangerous for people to avoid cancer screenings if those screenings do not impact life expectancy? You might want to know if you have cancer, but doesn't this suggest that...there's no baseline argument to suggest that all people undergo those screenings?
  - arisAlexis 3y ago
    They do impact life expectancy. The English language is a bit confusing to some mixed with statistics. They do not make life greater than average but they do make you closer to the average than if you die earlier.
glimshe 3y ago
If we are avoiding premature deaths for a subset of the population, wouldn't that by definition increase average life expectancy?
orblivion 3y ago
I mean, you could interpret that as "most cancer screenings don't extend life, because they come back negative". It's the "not most" case you're testing for in the first place.
- pessimizer 3y ago
  Not all positive tests are cancer. In some cases, actual cancers could be a tiny minority of positive tests. The tests themselves are a dangerous tool, and the way we minimize that danger is through statistics.
  - kccqzy 3y ago
    Then you are just changing one form of bad communication with another form. When a test indicates that there is cancer, the physician is not supposed to say "you have cancer" but rather "there is X% probability that you have cancer." If the test comes back negative, it should be "there is Y% probability that you have cancer" where presumably Y<X.
somenameforme 3y ago
The paper [1] is more well written and clear than the CNN article. They were comparing the aggregate life expectancies of people who went through regular screenings vs those who did not, and there was near zero difference except for colorectal screenings where the difference was about 4 months of difference. The paper is indeed presenting strong evidence that regular screenings have minimal value. [1] - https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2808648 https://jamanetwork.com/journals/jamainternalmedicine/fullar...
- hn_throwaway_99 3y ago
  Thanks for posting that. I read the article but not the paper, but I still feel like this may be a case where scientists "treat all time equally" in a way that most people do not, resulting in differing conclusions even though the data is the same. That is, putting aside monetary costs for the moment (which I know is not a good idea in reality, but want to focus on another issue), you often hear about how false positives cause "added anxiety and unnecessary treatments, which can cause harm", but if a breast cancer screening saves, say, lets one woman live until 80 instead of dying at 40, how many other people's "added anxiety" would it take to say "OK, that test was worth it". I think a lot of folks would go think that saving that life should be valued a lot more than just, say, comparing 40 years for her vs. time/anxiety "wasted" for false positives.
  - vc8f6vVV 3y ago
    X-ray is not just adding anxiety, it's harmful, and it's affecting all women who get screening, not only those who actually get cancer. Magic of numbers.
- francisofascii 3y ago
  > except for colorectal screenings where the difference was about 4 months of difference That sounds, uh, significant. So to clarify, does that mean people gain 4 months on average by getting this screening? Those who get the cancer gain years, and those that don't gain 0, so the average is 4 months?
kazinator 3y ago
If we decrease premature deaths from any cause, particularly a common cause of premature deaths, we increase life expectancy. Or just what do the authors think life expectancy means? It's an average. Every premature death drags down average life expectancy. If we say that cancer screening has no effect of life expectancy, that's exactly the same as saying that it doesn't prevent premature deaths. If cancer screening effectively prevents premature deaths, but the effect on the population's life expectancy is small, that effect is the wrong thing to be focusing on, potentially resulting in a harmful takeaway message.
- LorenPechtel 3y ago
  No, because we might be replacing one cause with another. That's what they've found with PSA--it kills (via treating things that wouldn't actually have killed the patient) as many as it saves.
  - kazinator 3y ago
    > That's what they've found with PSA--it kills (via treating things ...) I'm not sure what PSA you're referring to. The Prostate-Specific Antigen PSA is something secreted by the body, and not a treatment, so it can't be that one. Are you referring to overdiagnosis (via PSA or any other screening), resulting in overtreatment?
    - LorenPechtel 3y ago
      PSA is also commonly used to refer to the test that measures the PSA level. And, yes, it's treatment of things that weren't actually going to kill the patient. It's been known for quite a while that doing the test for screening produces no increase in life expectancy. What this study is saying is that the same problem seems to apply to most other cancer screenings.
- vc8f6vVV 3y ago
  You may be decreasing premature deaths from cancer but increasing premature deaths from other causes related to screening, thus you don't increase life expectancy. Read the original article in JAMA.
raverbashing 3y ago
Then the way this is being divulged is absolutely a very bad way Yes, life expectancy should count premature deaths Saying it "doesn't extend live" goes against that, because it absolutely does increase life expectancy Science communication is bad
teleforce 3y ago
There's only two things that are certain in this world, death and taxes - Benjamin Franklin. The main purpose of screening for early disease or genetic condition detection regardless of the diseases or illness, cancer, heart attack, stroke, etc, is not really to prolong longevity, even though that's a wonderful side effect, but the main thing to prevent complication(s) that may arise from the late detection. Apparently death does not incurs extra and massive medical bills, on the other hand complications will certainly do. If you connect the dots, this suddenly become a really good and plausible conspiracy theory. It's a shame that most of the health organizations, I'm looking at you American Heart Association (AHA), are really against any form of routine screening [1],[2]. [1] American Heart Association 14-Element Screening (Maron, BJ Circulation 2014): https://med.stanford.edu/content/dam/sm/ppc/documents/HSupervision/AHA_14-point.pdf https://med.stanford.edu/content/dam/sm/ppc/documents/HSuper... [2] ACC/AHA Release Recommendations For Congenital and Genetic Heart Disease Screenings in Youth: https://www.acc.org/latest-in-cardiology/articles/2014/09/15/14/24/acc-aha-release-recommendations-for-congenital-and-genetic-heart-disease-screenings-in-youth https://www.acc.org/latest-in-cardiology/articles/2014/09/15...
- vc8f6vVV 3y ago
  Just curious, have you read the original article in JAMA?
vc8f6vVV 3y ago
Have you read the original article, not the CNN interpretation? They are talking about harm vs benefits of screening. In simple words: you performed colonoscopy, got colon perforation and died of complications. Was colon cancer prevented? Absolutely! You didn't die of colon cancer! Is it any easier? No, it's not. The chance of dying of breast cancer is around 2.5%, so 1 women in 39 will die from that. OTOH annual X-rays affect the other 38 too, how many of them will die from X-ray exposure (which can cause e.g. another type of cancer, not necessary breast)? For the sake of discussion let's say 1 in 380. Congratulations, you've just increased breast cancer related death by 10%! Only it won't be in statistic as deaths from breast cancer.

chipsrafferty 3y ago

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monero-xmr 3y ago

An excellent episode of EconTalk came out today on this very subject: Open: https://simplecast.econtalk.org/episodes/vinay-prasad-on-cancer-screening https://simplecast.econtalk.org/episodes/vinay-prasad-on-can... Apple: https://podcasts.apple.com/us/podcast/econtalk/id135066958?i=1000625920965 https://podcasts.apple.com/us/podcast/econtalk/id135066958?i... Highly recommend the episode and show. The gist is that cancer is only 4% of deaths, and screening only reduces those 4% by 20% (so it does not help whatsoever 80% of cancers). But there is a lot more to the episode. The most important thing you need to do to prevent early death is reduce heart attack and stroke, and that requires better diet and exercise. Really the best drug of all is diet and exercise.

kiba 3y ago
Exercise also reduces cancer risk.
Retric 3y ago
Those numbers seem really off. The US has 3,464,231 deaths per year with cancer killing just over 600k, so 17.3%. https://www.cdc.gov/nchs/fastats/deaths.htm https://www.cdc.gov/nchs/fastats/deaths.htm https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/cancer-facts-figures-2021.html https://www.cancer.org/research/cancer-facts-statistics/all-... Also cancer screenings happen in the US. Thus 750k deaths without screenings and 80% of that = 600k deaths with screenings and 150k deaths postponed. Are they using some unusual definition or something?
- rocmcd 3y ago
  The 4% GP quoted was in reference to individual cancers (since there is no "cancer" screening, each screening is specific to a type of cancer). I'm having trouble finding numbers, but the comment by Vinay was basically saying that each screening is testing for something that has 1-4% chance of killing you. Not that 4% of all cause mortality is cancer, which is incorrect. In the context of individual screenings per cancer, the numbers roughly make sense based on what I could find, but I am by no means an expert. The specific video/content they are rehashing is the one by Vinay here - https://www.youtube.com/watch?v=-9hQO7X1bmU https://www.youtube.com/watch?v=-9hQO7X1bmU I'd highly recommend listening to the Econtalk conversation as there is a lot of nuance behind why screenings (at least as they are done today) could potentially be a net negative at the individual level and don't seem to have improved all-cause mortality in a significant way (according to Vinay).

twoodfin 3y ago

I am skeptical of the implied lesson of this analysis—and it is a meta-analysis of other research, not an original study. Just take as given that the analysis is correct, and screening for rare Disease A on net has no effect on life expectancy. Almost no one actually gets Disease A, but everyone is screened for it, and that has some diffuse cost to life expectancy: Screen enough people enough times and someone will die in a car accident on the way to or from the doctor's office. More likely the screening crowds out other more net-beneficial medical testing or is taken as some false comfort to continue an unhealthy lifestyle. Modern cancer treatment, especially for the most common types (i.e. the most likely to be screened for) is very good, even if the cancer is caught later due to lack of screening. So even the folks who catch it early due to screening don't incur a benefit in many cases, further pushing down the life-expectancy win on average. Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome. If you're a public health authority in a utilitarian and budget-constrained mindset, sure, don't encourage screenings by the logic and findings of this analysis. But I don't think individuals should consider on-average-LE-negative screenings as something to avoid.

circlefavshape 3y ago
> Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome. I'd say this depends on the nature of the diffuse negative effects you mention - if it's car accidents on the way to the doctor's office that's one thing, but if it's people dying during surgery they actually didn't need that's another
pajep 3y ago
what are some cancer screening that one should actively pursue?
- SpaceManNabs 3y ago
  Speak with your doctor about this, especially because I am not one, but from what I understand, the ones that you have a family history for, are pre-diposed by environment, the common ones, and the ones caught by usual body checks / tests during check ups. Again, not giving advice but things you can start a conversation with your doctor with.

kazinator 3y ago

> But experts say this doesn’t mean you should cancel that colonoscopy or mammogram appointment. That can only be that these experts disagree with the study, because if it were properly conducted such that its findings are true, then in fact its conclusions do add up to skipping colonoscopies and mammograms. The study is saying that the diagnostic procedures have no effect on outcome. You should not waste time on procedures that don't change outcome.

hedora 3y ago
The article dismisses a population-wide life expectancy increase of 4 months from one of the screens. If that's your bar, then most preventative screening is probably not worthwhile.
- kazinator 3y ago
  If, say, only 5% of the people undertake that screening and manage to bring up the population expectancy by four months, then the actual effect could be over six years for screened individuals. It's pretty dishonest to be confusing the effect of screening by counting unscreened individuals. It's like claiming that seat belts don't work by looking only at fatality figures that don't inform to what extent seatbelts were worn.
- wnissen 3y ago
  It would really help me to use the same methodology but compare it to people smoking like they did in the 1980s.

retrocryptid 3y ago

Wow. People really are bad at reasoning about probabilities. A more important question might be "does not getting cancer treatments lead to a shortened lifespan?" And that is exactly the question they did not ask in that study.

aydyn 3y ago

> explained that if breast cancer caused 3% of all female deaths and screenings reduced these deaths by 35%, that’s a good result on its own. But screenings may change mortality overall by only about 1% This statement makes it clear what's going on. In ML terms: class imbalance. 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. It won't make any statistical difference in overall population survival. But for the 0.1%? It will save their lives.

hedora 3y ago
Yes, and if you perform dozens of tests per year on the general population, and take action based on the results, then the probabilities add up pretty rapidly.
ilya_m 3y ago
I understand the comment's thesis, but I'd like to see more accurate numbers used where real health outcomes are concerned. The lifetime risk of being diagnosed with colorectal cancer is ~4%. (With the odds trending higher for the younger generation.) The risk of _death_ from this cancer is ~1%.
vc8f6vVV 3y ago
> 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. But they may have complications from a colonoscopy, that's the idea. No test is completely harmless, even a blood work. You save some lives but may loose others, that's the point of the paper. And of course you waste resources that can be used to find a cure.

apsec112 3y ago

Me before reading: "this study, like ~every study, will detect no effect on all-cause mortality because that needs a crazy big sample size" After reading: "this study, like ~every study, detected no effect on all-cause mortality because that needs a crazy big sample size" A three-year study where one group magically had zero car crashes would need a sample size of 5,000,000 to detect a difference in all-cause mortality. It's really hard. (80% chance of p < 0.05)

hedora 3y ago
They actually did show an improvement of all-cause mortality for one of the screens (corresponding to a 4 month increase in life expectancy), and "insignificant" improvements in others. (The headline is probably technically true, but I think it is intentionally misleading and disingenuous.)
deleted 3y ago
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hedora 3y ago

This article uses extremely contorted logic. Pretty much all health care has some cost, and hopefully some benefit in terms of life expectancy and/or quality-of-life-adjusted life expectancy. If you assume all the costs are fungible, then the analysis is straightforward (the costs are not actually fungible -- some things cost money, other things cost patient time, or use resources that are in finite supply -- so it turns into a linear programming problem, and we've been able to solve those since before computers existed). With fungible costs, for each of the available health care services, you the expected increase of life expectancy and divide it by the cost, and prioritize the things that have the highest benefit/cost ratio. The article doesn't talk at all about the cost of the screens, which is fairly low (vs. spending time exercising, or a year of exotic chemo). It also doesn't look at patient quality of life.

wkat4242 3y ago

Still it's nice to be the one outlier. For those with higher risk it would still be a good idea. Smokers, people who work with chemicals etc.

neongodzilla 3y ago

Sounds like a talking point one would use if you no longer wanted to provide coverage for preventive care.

deleted 3y ago

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porcoda 3y ago

(Note: very US centric comment here) I’ve become skeptical of the motives behind any article that seems to seed some level of doubt about health screenings and any preventative or treatment measure that involves the healthcare system itself. They always stink of the insurance and for-profit healthcare system and their aversion to paying anything out beyond the absolute bare minimum to get people the care they need. I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven.

highwayman47 3y ago
Ya exactly, I’ve had 2 family members catch pancreatic cancer early and be cured. It’s typically the most fatal cancer.
- DonsDiscountGas 3y ago
  This study did not look at pancreatic cancer.
DonsDiscountGas 3y ago
I can see why insurance companies might not want to pay, but the people selling the screenings absolutely would want you to get screened. I dunno about all types of cancer (and screening methods), but mammograms definitely are not helpful and this has been known for a long time [0] [0] https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagnosis https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagn... (2015)
andrekandre 3y ago
> I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven. in japan some prefectures or cities will send you leaflets/guides about how to get prescreening for cancer markers and early treatment for people past a certain age i seem to also remember seeing they offer incentives like first screening only 700 yen (about 5 bucks) etc so, yea, different systems, different incentives i guess
3y ago

amluto 3y ago

The actual study is (after some URL sanitization): https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2808648 https://jamanetwork.com/journals/jamainternalmedicine/fullar... and I do not like it. It suffers from what I consider an extremely common problem in statistics: if you define the question poorly, then your output is garbage no matter how fancy or careful your analysis is. We can start with the beginning of the abstract: > Importance Cancer screening tests are promoted to save life by increasing longevity, but it is unknown whether people will live longer with commonly used cancer screening tests. I have never heard of a doctor suggesting a cancer screening by saying "this might save your life by increasing your longevity." What does that even mean? So let's try to figure it out. The paper uses the terms "lifetime" and "longevity" somewhat interchangeably, and it does not define either term. The best I can figure out is that, for an individual deceased person, they have a certain lifetime in days from when they were screened to when they because deceased. (Or a certain lifetime in days from birth to death, and I'm not sure this distinction matters.) Great, but this is only for one patient. What about for a sample of patients or for a population in general or for the probability distribution of lifetimes of a given patient conditioned on whether they do or do not get screened? The article does not say, and a single "lifetime" number is not a probability distribution. Is it an expected value or a mean? A median? A mode? No comment. One of the headline conclusions is: > Based on the observed relative risks for all-cause mortality and the reported follow-up time in the trials, the only screening test that significantly increased longevity was sigmoidoscopy, by 110 days (95% CI, 0-274 days) (Table 2, Figure 2) Figure 2 is useless. Table 2 is somewhat informative, and it has a column for relative risk of all-cause mortality and a column for lifetime gained and its 95% CI. But WAIT A MOMENT! The only way you can know the lifetime of an individual patient is if they're dead. If they're dead, their risk of all-cause mortality by the time they died is 100%. That's not 100% plus or minus something with some relative risk thrown in -- they are dead enough to have a date of death so that someone could compute their lifetime! Or maybe "lifetime" means something else, and the authors didn't bother to figure it out and say what they meant. So what exactly is this paper even analyzing? So I suspect this is a meta-analysis of studies, of which some may or may not have been high enough quality to define their terms, and probably several of which used "lifetime" to mean some estimated property of a distribution, and this meta-analysis completely failed to figure out what the included studies were talking about. So I rate this meta-analysis as almost entirely useless, on account of it failing to actually analyze anything that makes sense. So I don't think any conclusions can be drawn. Although... ACS puts the lifetime risk of colorectal cancer at 1:25 or so. So one might naively translate a 110-day lifetime extension for everyone to a 110 day · 25 = 2750 day = ~7.5 year expected lifetime extension for people who actually get colorectal cancer. Sign me up -- 7.5 more expected years of life and presumably more than that of quality life years in the event I contract a not-particularly-rare disease sounds like a pretty good deal. (Colorectal cancer screening is not all that unpleasant, and I apparently only have a 96% chance of the screening being unnecessary.)

arisAlexis 3y ago

These articles are dangerous for the public. They may not go to have their regular checkups that will make them die younger and thus ironically yeah their life would not be extended any more.

dang 3y ago

Recent and related: The real cost of a preventive health scan goes well beyond the price tag - https://news.ycombinator.com/item?id=37266189 https://news.ycombinator.com/item?id=37266189 - Aug 2023 (254 comments)

arisAlexis 3y ago

There is a really weird connotation with this: if when malignancy is found and then actions are taken and when it's found earlier actions are taken earlier but they still don't survive means that when you treat a cancer early is the same as treating it late. But that is contrary to all studies ever done. So either there is some mistake or stage I with stage 3 cancer have the same survival. Look like someone fucked up some math imo.

michael1999 3y ago
It could also mean there are other negative forces balancing out the positive forces. Negative outcomes for broad screening include. - Early testing means more visits to the hospitals/clinics. Those are famously dangerous places to get sick. - False positives mean unneeded treatment. That can shorten your life. - Finding things earlier also means earlier treatment. That can kill you. Every trip to a hospital means a non-zero risk of catching MRSA and other nasties. - Some things would be handled by the immune system anyway. The treatment might provide no benefit over an ignorant outcome. I also find it easy to believe that among all the oncologists and hospitals, some of them might be at best neutral, or even net-negative in mortality and morbidity. This is about the whole population, not just leading units at famous hospitals. There are doctors out there with the ethics of a bent mechanic.

Flatcircle 3y ago

Breast cancer screens def save lives. Can't speak to all screenings but some def work.

flarg 3y ago
Evidence?
- haldujai 3y ago
  It's unequivocal that screening reduces breast-cancer specific mortality. None of the studies are powered enough to draw a positive or negative conclusion for overall mortality. The second last link is an explanation of why this is the case, where we're at and what the implications are. The last link explains the NCCN rationale and decision making process. http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b026a29-1.pdf http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b02... https://www.nejm.org/doi/full/10.1056/nejmoa1000727 https://www.nejm.org/doi/full/10.1056/nejmoa1000727 https://academic.oup.com/jnci/article/106/11/dju261/1496367?login=true https://academic.oup.com/jnci/article/106/11/dju261/1496367?... https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xml?print https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xm...
giarc 3y ago
"mammography screening did not prolong life" from the abstract. If you are unfortunately talking about a personal experience, sorry, but you can't confuse n=1 stories with large research studies.
teuobk 3y ago
Except breast cancer screening, at least via mammography, doesn't save lives. See, for example: https://thennt.com/nnt/screening-mammography-for-reducing-deaths/ https://thennt.com/nnt/screening-mammography-for-reducing-de...
- bironran 3y ago

jbandela1 3y ago

What surprising to me is that sigmoidoscopy shows a benefit but colonoscopy doesn’t. In colonoscopy, the entire colon is examined by using a long flexible tube. In sigmoidoscopy, only the lower portion of the colon is checked, again by using a flexible tube. The things that come to mind is that sigmoidoscopy may be better tolerated by patients or have fewer complications.

giarc 3y ago
Likely that the cancers found by the sigmoid are the ones that reduce life years. Perhaps the cancers that are found and treated higher up the colon would have been found out in other ways or not serious enough? I'm not a doctor, so not sure.
- psychphysic 3y ago
  Indeed there are dramatic differences between ascending and descending colon cancers. They are also dissimilar in their chances of presenting early with symptoms making screening less useful vs those that don't present early. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/

kwhitefoot 3y ago

The patient is not interested in the effect on the average life expectancy of all people in society, they are only interested in their own case when they are diagnosed early enough to have treatment that will extend their life if they have cancer. This is a different sub-population.

haldujai 3y ago
That's not the criteria for population level interventions. This is to answer the question of whether should the USPSTF make a positive recommendation and force insurers to pay or if public health systems should adopt this. You're conflating this with individual patient decisions.

memonkey 3y ago

What's the next question then? Curious to know if any of these screening caught cancers at various stages and if there is a correlation to better long term prognosis.

psychphysic 3y ago

This is not an unexpected result. Last I checked breast self examination also does not reduce deaths from breast cancer, nor testicular self examination. If anyone's interested the "Wilson criteria" is the basis of decisions about screening programmes and many run programmes fail it.

stevehawk 3y ago

Is this study just proving that other things kill you while you're being or after you've been treated for cancer?

trgn 3y ago
It provides evidence that a diagnostic approach to healthcare misunderstands that good health is a complex expression of a million factors, and not a function of the number of healthcare interventions. A diagnostic approach to healthcare can be easily bureaucratized (come collect your stamp after your colonoscopy!). A touchy-feely "million factors" approach cannot.
csours 3y ago
Someone else linked to https://thennt.com/nnt/screening-mammography-for-reducing-deaths/ https://thennt.com/nnt/screening-mammography-for-reducing-de... Quote: > "Two recent data reviews deserve further mention. The United Kingdom commissioned an independent review after dissenting voices swelled, for the purpose of better informing shared decision making and educational materials about the harms and benefits of screening.6 Unfortunately the review concluded that screening mammography trials were inadequately powered to detect an impact on all-cause mortality, and therefore used breast cancer mortality as a primary outcome. They concluded a 20% reduction and used this in their discussion of harms and benefits. As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether). Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed." > "They concluded a 20% reduction and used this in their discussion of harms and benefits." We want to do things that will help people. On an individual level, people have the right to make decisions for themselves. At the population level, we should do things that can be proven to be helpful. This leads to decisions that feel heartless - denying people a vaccine during a deadly pandemic while it is being tested; delaying or denying introduction of a new medicine that shows only marginal improvements over an old one. So their independent review showed benefit by changing the criteria for comparison. We want to help people, and medical interventions feel like helping. Unfortunately, sometimes they can be the equivalent of The Politician's Fallacy: "There was a problem. I did something about the problem. Therefore the problem is fixed" > "As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether)." People die of /something/. That thing becomes a target to fix; and we deploy resources to fix it. We become emotionally connected to some interventions. (Speaking personally, I'm participating in a bike ride in a few weeks to raise money for breast cancer screenings.) Some of those resources are beneficial, some are not, some may be harmful. > "Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."

bironran 3y ago

Does that mean early cancer treatments don't prolong life? Positive screening result usually leads to treatment of one kind or another. Without screening, treatment would start later, if at all. Is that a corollary of this study?

michael1999 3y ago

discussed here - https://news.ycombinator.com/item?id=37296122 https://news.ycombinator.com/item?id=37296122 I found this comment useful: - https://news.ycombinator.com/item?id=37297963 https://news.ycombinator.com/item?id=37297963 Several comments noted that a 4 month improvement in life expectancy (for sigmoidoscopy) over the whole population is actually pretty good for a low-incidence cancer. That's several years for the people who actually get it. But the comments seem naive about the downsides of broad screening: over-treatment, iatrogenic disease, false positives, opportunity cost, etc.

dang 3y ago
(this comment was originally posted to https://news.ycombinator.com/item?id=37312540 https://news.ycombinator.com/item?id=37312540, but we've merged that thread hither. that's why the comment links to its own thread now)

0cf8612b2e1e 3y ago

> In this systematic review and meta-analysis of 18 long-term randomized clinical trials involving 2.1 million individuals, colorectal cancer screening with sigmoidoscopy prolonged lifetime by 110 days, while fecal testing and mammography screening did not prolong life… That is shockingly bad. An extra three months of life is not nothing, but not exactly a clear win to push people towards the added stress and effort to be screened.

op00to 3y ago
What about quality of life? Colon cancer did not kill my wife's Grandma, but complications of the surgery did.

freedude 3y ago

My wife's grandpa was diagnosed with prostate cancer. He was 82 and had been a natural food store owner for over 30 years. He said the side effects to the treatment and the surgery was too great for him to endure and would impede his quality of life. He passed away 4 years later from pneumonia unrelated to the cancer. The cancer wasn't easy to deal with in those four years. He wasn't cut up and on chemo or radiation either. I agree with him in that too much can be "done"

xp84 3y ago

I am still disturbed by this though. The alternative I see to "get screenings" is "get no screenings." If you're one of the ones who actually do have an aggressive cancer, and you don't find out about it until it's like Stage Four, then you just definitely die, badly and soon. You, specifically, might have been helped if screened when you had a little baby tumor. So, while I see the "statistically" part, asking everyone to get zero screenings until you start coughing up blood (or whatever happens when the cancer starts showing very obvious signs)... it just seems weird on the individual level. Nobody knows (nor can they know) if you're the person who would be cured with treatment, or if you're the person whose outcome wouldn't have changed a bit with treatment (for better or for worse). That question matters individually, and while "statistically you're slightly more likely to be in the second group" according to these studies, that doesn't make me feel great about just declining all screenings.

vc8f6vVV 3y ago
> You, specifically, might have been helped if screened when you had a little baby tumor. Or your screening might have caused that tumor? X-rays are not harmless and they can cause cancer. Other screenings have their respective complications. Aren't you disturbed by a thought that maybe you wouldn't have any cancer if not for screening? Or you would have a healthy colon if not for the intern who perforated it during colonoscopy?