13 ms·

Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

230 points by benchtobedside 4y ago

donohoe 4y ago
I personally advise everyone to get a colonoscopy. I personally know 4 people who had the procedure and cancer was detected. Some further along than others. All still living. Colonoscopy is one of the few procedures that as they screen they can also take action.
- ljf 4y ago
  This. My father had a faecal test which showed he possibly had cancer - the colonoscopy confirmed this. Sadly my oldest brother didn't catch his so quickly and the colonoscopy he had showed he was pretty far along, and ultimately the cancer spread and killed him. I now have one every 5 years until I hit 50 then I'll move to every 2 years. The test is pretty pain and issue free, the only 'bad' part if the laxatives first, but after seeing my brother die, it is well worth the couple of hours of discomfort. My older brothers had continued with faecal testing, but after some pushing moved to colonoscopies too, as we'd rather catch it early, than once it has taken hold.
- droopyEyelids 4y ago
  Your comment is an example of the statistical/scientific misunderstandings that lead to 'overdiagnosis' https://www.cancer.gov/publications/dictionaries/cancer-terms/def/overdiagnosis https://www.cancer.gov/publications/dictionaries/cancer-term... Not all cancer is the same. Every person will have some amount of cancer as they get older. Some of the cancer will not be aggressive or disruptive enough to cause a problem before the person dies of another old-age related infirmary. Treating cancer is not free. Treatment reduces the quality of life of the person treated. Elderly people are slower to heal, and more at risk for complications. To treat a cancer that would not cause problems in the natural lifespan of its host is an expensive mistake. Screening technology can expand our ability to detect cancer without giving us the insight to know dangerous cancer from inconsequential cancer. When we go on to treat inconsequential cancer we've actually reduced the years of healthy life of the patient.
  - donohoe 4y ago
    I take your point, but 2 of the people I refer to had serious stage of cancer and would have died otherwise.
- theptip 4y ago
  Please be aware that the procedure is not risk-free and there is general concern in the medical community that it does more harm than good in healthy adults. 5/1000 colonoscopy patients have complications (some fatal) which is way higher than the base rate for colon cancer. It’s not a harmless screen like a mammogram.
  - gjreda 4y ago
    > 5/1000 colonoscopy patients have complications (some fatal) which is way higher than the base rate for colon cancer. Can you provide a source for this?
    - theptip 4y ago
      I copied that stat from the link I posted in another comment: https://news.ycombinator.com/item?id=33153494 https://news.ycombinator.com/item?id=33153494
deleted 4y ago
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bryan0 4y ago
> When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death. I’m really confused by this data. First of all, are they testing the efficacy of colonoscopy or the efficacy of inviting people to colonoscopy? And then how is the former group’s reduction in deaths 50% and the latter group’s is about 0%?
- hannob 4y ago
  They're doing an intention to treat analysis, which can be a bit confusing, but statistically makes sense and is the gold standard for clinical trials. You're basicall saying "our randomization at the beginning of the trial is key to avoid biases, so we can't reassign people from the treatment group to the other group, even if they practically don't get the treatment". The reason is if you allow people to switch, your assignment is no longer random. People who avoid the treatment may have different health properties than the ones who don't. In essence, you need your trial to be robust and large enough that a few people not getting the treatment don't matter.
  - bryan0 4y ago
    Thanks. That explanation on avoiding selection bias makes sense, but it seems like the study is saying those who choose to get a colonoscopy (whether invited or not) are 50% less likely to die of colon cancer. Also I’m not sure if the article mentioned this, but the data seems to imply that the % of people who opted to get a colonoscopy was similar in the invited and control group.
    - akvadrako 4y ago
      That suggests something strange though – that those who were invited but non-tested were more likely to die of colon cancer than non-invitie non-testers.
      - zerocrates 4y ago
groceryheist 4y ago
Sensationalist title to a good news story: there was no intent-to-treat effect, but a low conversion rate. The ETT is a pretty impressive 50% mortality reduction. Also study is limited by a short 10 year follow-up period but there will be a 15 year follow up. So I'll still get my colonoscopy, thanks
- rippercushions 4y ago
  Where are you getting "50% mortality reduction" from? The article says the reduction was zero: > After 10 years, the researchers found that the participants who were invited to colonoscopy had an 18% reduction in colon cancer risk but were no less likely to die from colon cancer than those who were never invited to screening.
  - tylermenezes 4y ago
    > When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death
    - Someone 4y ago
      I don’t see how that says much about the usefulness of colonoscopy. The people in the treatment group who didn’t show up must have had a 36% increase in colon cancer death (not explicitly stated in the article, but can be derived from the numbers. You need 42% × 50% + 58% × ? = 1), and (solving 42% × 70% + 58% × ? = 1) a 21% increase in colon cancer risk. Something must have made them different from the control group. Maybe, they didn’t show up because they already were being treated for colon cancer?
- JamesBarney 4y ago
  When everyone invited for a colonoscopy is compared to the control group 42% showed up and got a colonoscopy 18% fewer people got colon cancer same number of people died of colon cancer When everyone who got a colonoscopy is compared to the control group 30% fewer got colon cancer 50% fewer people died of colon cancer This data makes me think the mortality reduction benefit is bogus, but the cancer prevention benefit is real, and probably greater than 18%, maybe closer to 36-40%. If the colon cancer mortality benefit was real you'd see some reduction in the intention to treat group, and it'd be smaller than the cancer prevention effect. (The most aggressive cancers tend to be harder cancers to catch in time because they most so quickly, so most cancer screening tests will prevent more cancers than deaths)
cies 4y ago
Many years ago I learned about Japanese doctor Shinya. He pioneered the colonoscopy an found that diet was a big factor in intestinal health. Here some videos (may be NSFW): https://www.youtube.com/watch?v=B1LREA1ZuUE https://www.youtube.com/watch?v=B1LREA1ZuUE But there are lots more to see. I believe what he discovered is important. Not that I believe his advice to drink ionized water (Kangen water) is scientifically sound. But that does not matter for the discovery that switching to eat rice and veggies cleans your intestine.
theGnuMe 4y ago
Does the patient population play a role? I see mostly Europeans here. The Japanese have a higher colon cancer rate, what percent die there?
calderwoodra 4y ago
> The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group IIUC, there was still a reduction in colon cancer deaths, but the populations still experienced the same % of deaths from all causes. https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375
pazimzadeh 4y ago
> If the endoscopist discovers a suspicious polyp, then it’s promptly removed, thus nipping the cancer before it spreads So, kind of like how pruning a plant does not necessarily weaken it.
- Findecanor 4y ago
  When the polyp has been nipped, it is gone. If you have a colon with no polyps (left) in it, you should be safe from colon cancer for at least a decade (how long polyps take to develop from mutation into a tumour).
  - pazimzadeh 4y ago
    If that's the case, then why was there no difference in mortality in the study? Possible reasons I thought of: - cancer cells metastasize/spread much earlier than we previously thought (https://www.statnews.com/2016/12/14/cancer-cells-spread-metastases/ https://www.statnews.com/2016/12/14/cancer-cells-spread-meta...) - what if the presence of polyps is not all bad? i.e. maybe they keep the immune system in a tumor-responsive state, or they locally deplete nutrients that would otherwise feed other pre-cancerous cells?
deleted 4y ago
[deleted]
em500 4y ago
Several posters have criticized the title of the news article "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths". The actual study is titled "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death" [1] The authors conclude that "In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. " I find it generally more useful link to the (abstract) of the original article, rather than second hand news reports. The abstracts are usually pretty accessible for a somewhat technical audience, they're not written for domain experts only. As we see in the discussions here, it's questionable whether the rephrasing from journalists really adds anything. [1] https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375
- hef19898 4y ago
  That makes so much more sense and would lead to a much better discussion. Any chance the title and linked site can be changed? It does show quite nicely how one can lie through scientific studies and confuse people.
- ricardobeat 4y ago
  There is nothing wrong with the title. The study failed to find a reduction in death rate despite lowering the incidence of cancer, and that is the center of the piece. It goes into detail of why this is surprising. The study authors were interviewed and agreed. The reporting actually adds a lot of context that you would never get from a link to a random study. Like, for example, how it is called the “gold standard” because it’s a 10-year large scale randomized trial, and the doctors running the study are the ones who promoted colonoscopy as a tool to reduce cancer mortality in the first place.
  - em500 4y ago
    The problem with the title is that it might lead individuals to believe they shouldn't bother with getting a colonoscopy. You can't conclude that from this study at all. If your doctor recommends you to get one, you probably should. The study answers a question pertaining public health policy (should we invite everyone in some age group for a colonoscopy?). It does not answer any individual health/treatment/screening question. The article's headline and content is problematic because it's easy to confuse the two, and the vast majority of readers will never get involved in public health policy (but will certainly have to make lots of individual health decisions).
denton-scratch 4y ago
This is about colonoscopy screening. If you give a fecal sample and it comes up as suspicious, the next step will be a colonoscopy anyway. A colonoscopy is quite unpleasant; you starve for a day, and take an enema. They may sedate you before the procedure. If they don't, then the procedure is quite uncomfortable; not exactly painful, but unpleasant. Incidentally, if they find and remove a polyp, they will plant a tattoo inside your gut to mark the spot, for the benefit of future spelunking visitors.
- deleted 4y ago
  [deleted]
- lm28469 4y ago
  > you starve for a day fast for a day, starvation is another thing and takes weeks to set in for the average westerner
  - B1FF_PSUVM 4y ago
    "Hungry is after three days" as I once heard it ...
- adam-a 4y ago
  They can be very painful, in my experience. I would not opt for one without sedation again.
  - denton-scratch 4y ago
    Thanks for these corrections. Yes, I should have said "fast". And indeed for my recent colonoscopy, I was given laxative, not an enema, it's a sachet of powder that you dissolve in a litre of water; you then have to gulp that down as well as drinking lots of water. Years ago I had a sigmoidoscopy, and then they did give me an enema. That's the only time I've had an enema, and I didn't know what to expect. It was very rapid, and rather dramatic.
- seanmcdirmid 4y ago
  The enema is replaced with a laxative often. That is still really hard, I barely got half of mine down and was in a rough state the morning of the procedure. I was sedated, so laxative was the hardest part of the ordeal, not the fasting or actual procedure.
iampivot 4y ago
"Gold-standard trial" sounds about as good as Genuine Leather does for leather. (Genuine leather is the cheapest leather, for those that don't know).
- jugg1es 4y ago
  If you had a science background, the term "Gold-standard trial" would have meaning to you as a term for randomized double-blind studies with a large sample size. I don't know what textiles have to do with it.
mrtri 4y ago
Nokinside 4y ago
Years ago I learned that this is the reason why they don't do colonoscopies without good reason in Finland. I asked from a doctor who is a friend why you have regular colonoscopies in the US but not in the Finland and he said "no evidence and colonoscopy has a small risk factor". If you do medicine for profit and are allowed to advertise and market, doing more is always better.
- dis-sys 4y ago
  as reported by the article, an impressive 50% reduction of cancer death for those who did colonoscopy. I call that solid evidence which could potentially save millions of real lives.
  - darkerside 4y ago
    Not included in the study is data about how many other screenings those people did
  - theptip 4y ago
    Not reported, how many people died from side effects of the procedure, such as blood poisoning/infection. We care about all-cause mortality, not cancer mortality.
    - FinnLeSueur 4y ago
      I haven't read the article - only the abstract, but it does report: "No perforations or screening-related deaths occurred within 30 days after colonoscopy." I guess something could have happened later than 30 days but we'd need the full article for that.
dis-sys 4y ago
the result reported by the article is impressive - 50% reduction in cancer death for those who actually did at least one colonoscopy in 10 years. surely your risk can be further reduced by having annual colonoscopy if you are in the high risk group, e.g. with family history.
Traubenfuchs 4y ago
You might not die if you leave that cancer alone, but you might get part of your colon removed, or get a colostomy bag, or get your anus surgically sewn shut til death -all of which not necessarily changes your life expectancy. Looking for death vs no-death alone as an outcome for medical diagnosis/treatment is short sighted.
ricardobeat 4y ago
From the HN guidelines: > please use the original title, unless it is misleading or linkbait; don't editorialize I'm finding myself disappointed with the application of guidelines here. The title has been changed to a completely made up headline, differing from the original, which is editorializing. It's the second time this happens in the past 24 hours - yesterday the ".. you idiot" part was removed from a blog post completely numbing the post's intention. Neither was misleading or clickbait. EDIT: while typing this comment, the title has been changed yet again to reflect the paper's title "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death".
- benchtobedside 4y ago
  This post was submitted with the following title from the original article per the guidelines: "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths"
  - ricardobeat 4y ago
    Exactly. There was no need to edit.
m0llusk 4y ago
This is a very complex subject because the sensitivity of tests for colorectal cancer has improved over time and more testing is being done. This makes it appear as if there is a great increase in colorectal cancer when there really isn't. A very interesting related study has become known as "The Norwegian Colorectal Study" found that early testing was a waste of money since only those with a family history of colorectal cancer or IBS symptoms or both actually got colorectal cancer before 55. For most people the polyps which are precursors to colorectal cancer do not appear before age 55. That means that the current push for aggressive testing starting at 50 is a distracting waste of time, money, and effort that should be eased back.
- ravel-bar-foo 4y ago
  There have been some really interesting studies which showed that in order to get colorectal cancer you have to accumulate 4-6 deletrious mutations in the same cells. People with genetic predispositions are born with 2-3 of those mutations. That's why we see this age association. (Just remember being fascinated and thought I would add some context.)
AlphaOne1 4y ago
Vinay Prasad, MD (Heme/Onc) gives a very good rundown on why this trial is so important. He also points out why having accurate data for screening recommendations is so crucial. USPTF has been making recommendations recently without data to back up them up and get appropriately taken to task for that. [1] https://m.youtube.com/watch?v=SMRS4-ng8T0 https://m.youtube.com/watch?v=SMRS4-ng8T0
- gilbetron 4y ago
  Beware Vinay Prasad: https://www.respectfulinsolence.com/2022/07/27/john-ioannidis-and-vinay-prasad-team-up-to-lecture-social-media-about-obsessive-criticism/ https://www.respectfulinsolence.com/2022/07/27/john-ioannidi...
  - wrycoder 4y ago
    That article is a great example of snarky pile-on. Remember: you’re not being paranoid, if they are actually out to get you.
  - wellbehaved 4y ago
    Beware David Gorski: https://stevekirsch.substack.com/p/how-david-gorski-defends-the-narrative https://stevekirsch.substack.com/p/how-david-gorski-defends-...
    - gilbetron 4y ago
      Beware Steve Kirsch: https://www.technologyreview.com/2021/10/05/1036408/silicon-valley-millionaire-steve-kirsch-covid-vaccine-misinformation/ https://www.technologyreview.com/2021/10/05/1036408/silicon-...
      - wellbehaved 4y ago
        "He prefers iconoclastic approaches, whether by directly funding asteroid detection or advocating for nuclear power to combat global warming." Ooh, scary dude. /s Kids nowadays. I remember when nuclear power was a futuristic clean energy sort of ideal and when the way we figured out who was right and who was wrong on a complex topic was to let both sides openly debate and then pick who is more credible by how each is able to rally the facts in defense of their position. Beware your society, which is doing the same thing to people like Kirsch that it did to Socrates two thousand years ago. The masses never change, apparently. All that changes is whether they're held in check or whether they're exploited by demagogues.
pelario 4y ago
“They’re doing a 15-year follow, and I would expect to see a significant reduction in cancer mortality in the long term,” Dominitz said. “Time will tell.” After all the debate here in HN about the interpretation of the data and the statistics, I'm really looking forward to see a post in 15 years with the new study.
et2o 4y ago
The problem with this study is that the analysis is based upon intention to treat. Only 42% of those who were randomized to get a colonoscopy actually got one. The cancer incidence was 18% lower among all people who were invited to get a colonoscopy. If we assume rate among people who were invited to get a colonoscopy but did not go through with it is the same as the rate of people who did not get a colonoscopy then the cancer rate would be more like -2/3 among those who got a colonoscopy.
brooklyndude 4y ago
I’m unique guess in the world. We’re all going to die. If you make it to 57, awesome. After that it’s all a bonus. Take that attitude, and you really don’t put off much. You don’t turn down any invites. And do wake up with the Sun. Life is awesome! Don’t be so afraid of death. It’s not that bad. Really. Source: survived an NDE. Was not my time was told, but did get a great tour of the afterlife. Don’t worry so much. And treat strangers with kindness, they were very insistent on that. They keep score. Heaven or Hell. It’s your decision. :-)
- 1123581321 4y ago
  I like your attitude, but it's hard to apply it to loved ones as cavalierly!
z9znz 4y ago
> The trial’s primary analysis found that colonoscopy only cut colon cancer risk by roughly a fifth Perhaps it was oversold, but a 20% reduction still seems significant.
tssva 4y ago
A lot of the comments here seem to come from the perspective that a colonoscopy is the only way to screen for colorectal cancer. There are also fecal sample tests such as FIT and FIT-DNA. Both involve home collection of fecal samples for testing. In the case of FIT yearly and FIT-DNA every 3 years. In the case of both if there is a positive result a colonoscopy is then performed. Outside the US annual FIT testing seems to be the standard of care versus a screening colonoscopy. A similar study with yearly FIT tests would be interesting to see. I suspect you might have a better compliance rate than the 42% seen in this study.
naasking 4y ago
Good discussion here, but I think the main message might get lost in the noise: * Colonoscopies reduce incidence of colon cancer but apparently not death from colon cancer. * This is probably because colon cancer therapies are good, so even if you get colon cancer your prognosis is good. * The take-away is not that colonoscopies reduce your chances of death, but that they reduce your chances of having to suffer colon cancer and subsequent therapies. That might still be a good trade-off.
rammy1234 4y ago
Title and end conclusion of the article are contradicting. Last paragraph says, "If you cannot take 2 days off, then you have other options. If you want to take test once in 10 years, Colonoscopy is the king". This means Colonoscopy is still the king if you can take 2 days off from your work ( which I believe most workers should be able to as this is important for one's life ). Not sure how this is beneficial for the readers of this article.
theptip 4y ago
I’m quite surprised in 2022 that news coverage is not mentioning the now well-known risks associated with colonoscopies. AIUI they are no longer recommended in the EU for routine screening because of the very high rate of dangerous side effects, on net increasing all cause mortality in the general population. The article here just looks at cancer mortality, which is not what anyone should care about. For more recent commentary, an example is https://blogs.scientificamerican.com/cross-check/why-i-wont-get-a-colonoscopy/ https://blogs.scientificamerican.com/cross-check/why-i-wont-...
noduerme 4y ago
Shouldn't this study properly be called "Effect of Offering Colonoscopy Screening on Risks..."? The headline result is based on the 18% decrease in CR cancer among people who were offered a colonoscopy. Of the people offered, only 42% actually got a colonoscopy. That means in the "colonoscopy group" 58% never even had one. Among those who did get one, there was a 31% decrease in CR cancer, and a 50% reduction in deaths from CR cancer. All the study really proves is that offering someone a colonoscopy isn't the same thing as giving them one.
alexjpb 4y ago
Irresponsible click bait title. If you are over 40,take a colonoscopy. I lost my brother (44) from colon cancer which could have been totally prevented. It was a very painful and depressing experience, multiple rounds of chemotherapy and surgeries that lasted over four years and sent his family into bankruptcy. He stopped eating solid foods weighing only 47 kilos and died from suffocation, pretty much liquid accumulating and pressing against his lungs until he could no longer breath. It's a slow and horrible dead that can be prevented with a simple one hour procedure done once every 5-10 years and in many cases 100% covered by insurance.
uslic001 4y ago
I would suggest reading the editorial also. Study has major limitations. From the doctor who wrote the editorial on Facebook Dr Jason Dominitz: "I'm honored to have been invited to write an editorial for the NEJM about the landmark NordICC study comparing screening colonoscopy to usual care (no screening) in Norway, Poland and Sweden. The NordICC results were somewhat disappointing in that colonoscopy only reduced colorectal cancer incidence by 18% at 10 years, with no significant mortality benefit. But only 42% of individuals who were invited to have a colonoscopy followed through. For those that did have colonoscopy, mortality was reduced by 50%. This study highlights the importance of adherence with screening. Also, we know that colonoscopy quality is variable and 29% of the endoscopists were not meeting quality benchmarks for polyp detection. So if you are getting a colonoscopy, ask your doctor what their "ADR" (adenoma detection rate) is. If they don't know, find another doctor to do your colonoscopy. The ADR should be well over 25% and, ideally, over 40%. " https://www.nejm.org/doi/full/10.1056/NEJMe2211595 https://www.nejm.org/doi/full/10.1056/NEJMe2211595 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375...

I personally advise everyone to get a colonoscopy. I personally know 4 people who had the procedure and cancer was detected. Some further along than others. All still living. Colonoscopy is one of the few procedures that as they screen they can also take action.

ljf 4y ago
This. My father had a faecal test which showed he possibly had cancer - the colonoscopy confirmed this. Sadly my oldest brother didn't catch his so quickly and the colonoscopy he had showed he was pretty far along, and ultimately the cancer spread and killed him. I now have one every 5 years until I hit 50 then I'll move to every 2 years. The test is pretty pain and issue free, the only 'bad' part if the laxatives first, but after seeing my brother die, it is well worth the couple of hours of discomfort. My older brothers had continued with faecal testing, but after some pushing moved to colonoscopies too, as we'd rather catch it early, than once it has taken hold.
droopyEyelids 4y ago
Your comment is an example of the statistical/scientific misunderstandings that lead to 'overdiagnosis' https://www.cancer.gov/publications/dictionaries/cancer-terms/def/overdiagnosis https://www.cancer.gov/publications/dictionaries/cancer-term... Not all cancer is the same. Every person will have some amount of cancer as they get older. Some of the cancer will not be aggressive or disruptive enough to cause a problem before the person dies of another old-age related infirmary. Treating cancer is not free. Treatment reduces the quality of life of the person treated. Elderly people are slower to heal, and more at risk for complications. To treat a cancer that would not cause problems in the natural lifespan of its host is an expensive mistake. Screening technology can expand our ability to detect cancer without giving us the insight to know dangerous cancer from inconsequential cancer. When we go on to treat inconsequential cancer we've actually reduced the years of healthy life of the patient.
- donohoe 4y ago
  I take your point, but 2 of the people I refer to had serious stage of cancer and would have died otherwise.
theptip 4y ago
Please be aware that the procedure is not risk-free and there is general concern in the medical community that it does more harm than good in healthy adults. 5/1000 colonoscopy patients have complications (some fatal) which is way higher than the base rate for colon cancer. It’s not a harmless screen like a mammogram.
- gjreda 4y ago
  > 5/1000 colonoscopy patients have complications (some fatal) which is way higher than the base rate for colon cancer. Can you provide a source for this?
  - theptip 4y ago
    I copied that stat from the link I posted in another comment: https://news.ycombinator.com/item?id=33153494 https://news.ycombinator.com/item?id=33153494

deleted 4y ago

[deleted]

bryan0 4y ago

> When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death. I’m really confused by this data. First of all, are they testing the efficacy of colonoscopy or the efficacy of inviting people to colonoscopy? And then how is the former group’s reduction in deaths 50% and the latter group’s is about 0%?

hannob 4y ago
They're doing an intention to treat analysis, which can be a bit confusing, but statistically makes sense and is the gold standard for clinical trials. You're basicall saying "our randomization at the beginning of the trial is key to avoid biases, so we can't reassign people from the treatment group to the other group, even if they practically don't get the treatment". The reason is if you allow people to switch, your assignment is no longer random. People who avoid the treatment may have different health properties than the ones who don't. In essence, you need your trial to be robust and large enough that a few people not getting the treatment don't matter.
- bryan0 4y ago
  Thanks. That explanation on avoiding selection bias makes sense, but it seems like the study is saying those who choose to get a colonoscopy (whether invited or not) are 50% less likely to die of colon cancer. Also I’m not sure if the article mentioned this, but the data seems to imply that the % of people who opted to get a colonoscopy was similar in the invited and control group.
  - akvadrako 4y ago
    That suggests something strange though – that those who were invited but non-tested were more likely to die of colon cancer than non-invitie non-testers.
    - zerocrates 4y ago

groceryheist 4y ago

Sensationalist title to a good news story: there was no intent-to-treat effect, but a low conversion rate. The ETT is a pretty impressive 50% mortality reduction. Also study is limited by a short 10 year follow-up period but there will be a 15 year follow up. So I'll still get my colonoscopy, thanks

rippercushions 4y ago
Where are you getting "50% mortality reduction" from? The article says the reduction was zero: > After 10 years, the researchers found that the participants who were invited to colonoscopy had an 18% reduction in colon cancer risk but were no less likely to die from colon cancer than those who were never invited to screening.
- tylermenezes 4y ago
  > When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death
  - Someone 4y ago
    I don’t see how that says much about the usefulness of colonoscopy. The people in the treatment group who didn’t show up must have had a 36% increase in colon cancer death (not explicitly stated in the article, but can be derived from the numbers. You need 42% × 50% + 58% × ? = 1), and (solving 42% × 70% + 58% × ? = 1) a 21% increase in colon cancer risk. Something must have made them different from the control group. Maybe, they didn’t show up because they already were being treated for colon cancer?
JamesBarney 4y ago
When everyone invited for a colonoscopy is compared to the control group 42% showed up and got a colonoscopy 18% fewer people got colon cancer same number of people died of colon cancer When everyone who got a colonoscopy is compared to the control group 30% fewer got colon cancer 50% fewer people died of colon cancer This data makes me think the mortality reduction benefit is bogus, but the cancer prevention benefit is real, and probably greater than 18%, maybe closer to 36-40%. If the colon cancer mortality benefit was real you'd see some reduction in the intention to treat group, and it'd be smaller than the cancer prevention effect. (The most aggressive cancers tend to be harder cancers to catch in time because they most so quickly, so most cancer screening tests will prevent more cancers than deaths)

cies 4y ago

Many years ago I learned about Japanese doctor Shinya. He pioneered the colonoscopy an found that diet was a big factor in intestinal health. Here some videos (may be NSFW): https://www.youtube.com/watch?v=B1LREA1ZuUE https://www.youtube.com/watch?v=B1LREA1ZuUE But there are lots more to see. I believe what he discovered is important. Not that I believe his advice to drink ionized water (Kangen water) is scientifically sound. But that does not matter for the discovery that switching to eat rice and veggies cleans your intestine.

theGnuMe 4y ago

Does the patient population play a role? I see mostly Europeans here. The Japanese have a higher colon cancer rate, what percent die there?

calderwoodra 4y ago

> The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group IIUC, there was still a reduction in colon cancer deaths, but the populations still experienced the same % of deaths from all causes. https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375

pazimzadeh 4y ago

> If the endoscopist discovers a suspicious polyp, then it’s promptly removed, thus nipping the cancer before it spreads So, kind of like how pruning a plant does not necessarily weaken it.

Findecanor 4y ago
When the polyp has been nipped, it is gone. If you have a colon with no polyps (left) in it, you should be safe from colon cancer for at least a decade (how long polyps take to develop from mutation into a tumour).
- pazimzadeh 4y ago
  If that's the case, then why was there no difference in mortality in the study? Possible reasons I thought of: - cancer cells metastasize/spread much earlier than we previously thought (https://www.statnews.com/2016/12/14/cancer-cells-spread-metastases/ https://www.statnews.com/2016/12/14/cancer-cells-spread-meta...) - what if the presence of polyps is not all bad? i.e. maybe they keep the immune system in a tumor-responsive state, or they locally deplete nutrients that would otherwise feed other pre-cancerous cells?

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em500 4y ago

Several posters have criticized the title of the news article "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths". The actual study is titled "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death" [1] The authors conclude that "In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. " I find it generally more useful link to the (abstract) of the original article, rather than second hand news reports. The abstracts are usually pretty accessible for a somewhat technical audience, they're not written for domain experts only. As we see in the discussions here, it's questionable whether the rephrasing from journalists really adds anything. [1] https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375

hef19898 4y ago
That makes so much more sense and would lead to a much better discussion. Any chance the title and linked site can be changed? It does show quite nicely how one can lie through scientific studies and confuse people.
ricardobeat 4y ago
There is nothing wrong with the title. The study failed to find a reduction in death rate despite lowering the incidence of cancer, and that is the center of the piece. It goes into detail of why this is surprising. The study authors were interviewed and agreed. The reporting actually adds a lot of context that you would never get from a link to a random study. Like, for example, how it is called the “gold standard” because it’s a 10-year large scale randomized trial, and the doctors running the study are the ones who promoted colonoscopy as a tool to reduce cancer mortality in the first place.
- em500 4y ago
  The problem with the title is that it might lead individuals to believe they shouldn't bother with getting a colonoscopy. You can't conclude that from this study at all. If your doctor recommends you to get one, you probably should. The study answers a question pertaining public health policy (should we invite everyone in some age group for a colonoscopy?). It does not answer any individual health/treatment/screening question. The article's headline and content is problematic because it's easy to confuse the two, and the vast majority of readers will never get involved in public health policy (but will certainly have to make lots of individual health decisions).

denton-scratch 4y ago

This is about colonoscopy screening. If you give a fecal sample and it comes up as suspicious, the next step will be a colonoscopy anyway. A colonoscopy is quite unpleasant; you starve for a day, and take an enema. They may sedate you before the procedure. If they don't, then the procedure is quite uncomfortable; not exactly painful, but unpleasant. Incidentally, if they find and remove a polyp, they will plant a tattoo inside your gut to mark the spot, for the benefit of future spelunking visitors.

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lm28469 4y ago
> you starve for a day fast for a day, starvation is another thing and takes weeks to set in for the average westerner
- B1FF_PSUVM 4y ago
  "Hungry is after three days" as I once heard it ...
adam-a 4y ago
They can be very painful, in my experience. I would not opt for one without sedation again.
- denton-scratch 4y ago
  Thanks for these corrections. Yes, I should have said "fast". And indeed for my recent colonoscopy, I was given laxative, not an enema, it's a sachet of powder that you dissolve in a litre of water; you then have to gulp that down as well as drinking lots of water. Years ago I had a sigmoidoscopy, and then they did give me an enema. That's the only time I've had an enema, and I didn't know what to expect. It was very rapid, and rather dramatic.
seanmcdirmid 4y ago
The enema is replaced with a laxative often. That is still really hard, I barely got half of mine down and was in a rough state the morning of the procedure. I was sedated, so laxative was the hardest part of the ordeal, not the fasting or actual procedure.

iampivot 4y ago

"Gold-standard trial" sounds about as good as Genuine Leather does for leather. (Genuine leather is the cheapest leather, for those that don't know).

jugg1es 4y ago
If you had a science background, the term "Gold-standard trial" would have meaning to you as a term for randomized double-blind studies with a large sample size. I don't know what textiles have to do with it.

mrtri 4y ago

Nokinside 4y ago

Years ago I learned that this is the reason why they don't do colonoscopies without good reason in Finland. I asked from a doctor who is a friend why you have regular colonoscopies in the US but not in the Finland and he said "no evidence and colonoscopy has a small risk factor". If you do medicine for profit and are allowed to advertise and market, doing more is always better.

dis-sys 4y ago
as reported by the article, an impressive 50% reduction of cancer death for those who did colonoscopy. I call that solid evidence which could potentially save millions of real lives.
- darkerside 4y ago
  Not included in the study is data about how many other screenings those people did
- theptip 4y ago
  Not reported, how many people died from side effects of the procedure, such as blood poisoning/infection. We care about all-cause mortality, not cancer mortality.
  - FinnLeSueur 4y ago
    I haven't read the article - only the abstract, but it does report: "No perforations or screening-related deaths occurred within 30 days after colonoscopy." I guess something could have happened later than 30 days but we'd need the full article for that.

dis-sys 4y ago

the result reported by the article is impressive - 50% reduction in cancer death for those who actually did at least one colonoscopy in 10 years. surely your risk can be further reduced by having annual colonoscopy if you are in the high risk group, e.g. with family history.

Traubenfuchs 4y ago

You might not die if you leave that cancer alone, but you might get part of your colon removed, or get a colostomy bag, or get your anus surgically sewn shut til death -all of which not necessarily changes your life expectancy. Looking for death vs no-death alone as an outcome for medical diagnosis/treatment is short sighted.

ricardobeat 4y ago

From the HN guidelines: > please use the original title, unless it is misleading or linkbait; don't editorialize I'm finding myself disappointed with the application of guidelines here. The title has been changed to a completely made up headline, differing from the original, which is editorializing. It's the second time this happens in the past 24 hours - yesterday the ".. you idiot" part was removed from a blog post completely numbing the post's intention. Neither was misleading or clickbait. EDIT: while typing this comment, the title has been changed yet again to reflect the paper's title "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death".

benchtobedside 4y ago
This post was submitted with the following title from the original article per the guidelines: "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths"
- ricardobeat 4y ago
  Exactly. There was no need to edit.

m0llusk 4y ago

This is a very complex subject because the sensitivity of tests for colorectal cancer has improved over time and more testing is being done. This makes it appear as if there is a great increase in colorectal cancer when there really isn't. A very interesting related study has become known as "The Norwegian Colorectal Study" found that early testing was a waste of money since only those with a family history of colorectal cancer or IBS symptoms or both actually got colorectal cancer before 55. For most people the polyps which are precursors to colorectal cancer do not appear before age 55. That means that the current push for aggressive testing starting at 50 is a distracting waste of time, money, and effort that should be eased back.

ravel-bar-foo 4y ago
There have been some really interesting studies which showed that in order to get colorectal cancer you have to accumulate 4-6 deletrious mutations in the same cells. People with genetic predispositions are born with 2-3 of those mutations. That's why we see this age association. (Just remember being fascinated and thought I would add some context.)

AlphaOne1 4y ago

Vinay Prasad, MD (Heme/Onc) gives a very good rundown on why this trial is so important. He also points out why having accurate data for screening recommendations is so crucial. USPTF has been making recommendations recently without data to back up them up and get appropriately taken to task for that. [1] https://m.youtube.com/watch?v=SMRS4-ng8T0 https://m.youtube.com/watch?v=SMRS4-ng8T0

gilbetron 4y ago
Beware Vinay Prasad: https://www.respectfulinsolence.com/2022/07/27/john-ioannidis-and-vinay-prasad-team-up-to-lecture-social-media-about-obsessive-criticism/ https://www.respectfulinsolence.com/2022/07/27/john-ioannidi...
- wrycoder 4y ago
  That article is a great example of snarky pile-on. Remember: you’re not being paranoid, if they are actually out to get you.
- wellbehaved 4y ago
  Beware David Gorski: https://stevekirsch.substack.com/p/how-david-gorski-defends-the-narrative https://stevekirsch.substack.com/p/how-david-gorski-defends-...
  - gilbetron 4y ago
    Beware Steve Kirsch: https://www.technologyreview.com/2021/10/05/1036408/silicon-valley-millionaire-steve-kirsch-covid-vaccine-misinformation/ https://www.technologyreview.com/2021/10/05/1036408/silicon-...
    - wellbehaved 4y ago
      "He prefers iconoclastic approaches, whether by directly funding asteroid detection or advocating for nuclear power to combat global warming." Ooh, scary dude. /s Kids nowadays. I remember when nuclear power was a futuristic clean energy sort of ideal and when the way we figured out who was right and who was wrong on a complex topic was to let both sides openly debate and then pick who is more credible by how each is able to rally the facts in defense of their position. Beware your society, which is doing the same thing to people like Kirsch that it did to Socrates two thousand years ago. The masses never change, apparently. All that changes is whether they're held in check or whether they're exploited by demagogues.

pelario 4y ago

“They’re doing a 15-year follow, and I would expect to see a significant reduction in cancer mortality in the long term,” Dominitz said. “Time will tell.” After all the debate here in HN about the interpretation of the data and the statistics, I'm really looking forward to see a post in 15 years with the new study.

et2o 4y ago

The problem with this study is that the analysis is based upon intention to treat. Only 42% of those who were randomized to get a colonoscopy actually got one. The cancer incidence was 18% lower among all people who were invited to get a colonoscopy. If we assume rate among people who were invited to get a colonoscopy but did not go through with it is the same as the rate of people who did not get a colonoscopy then the cancer rate would be more like -2/3 among those who got a colonoscopy.

brooklyndude 4y ago

I’m unique guess in the world. We’re all going to die. If you make it to 57, awesome. After that it’s all a bonus. Take that attitude, and you really don’t put off much. You don’t turn down any invites. And do wake up with the Sun. Life is awesome! Don’t be so afraid of death. It’s not that bad. Really. Source: survived an NDE. Was not my time was told, but did get a great tour of the afterlife. Don’t worry so much. And treat strangers with kindness, they were very insistent on that. They keep score. Heaven or Hell. It’s your decision. :-)

1123581321 4y ago
I like your attitude, but it's hard to apply it to loved ones as cavalierly!

z9znz 4y ago

> The trial’s primary analysis found that colonoscopy only cut colon cancer risk by roughly a fifth Perhaps it was oversold, but a 20% reduction still seems significant.

tssva 4y ago

A lot of the comments here seem to come from the perspective that a colonoscopy is the only way to screen for colorectal cancer. There are also fecal sample tests such as FIT and FIT-DNA. Both involve home collection of fecal samples for testing. In the case of FIT yearly and FIT-DNA every 3 years. In the case of both if there is a positive result a colonoscopy is then performed. Outside the US annual FIT testing seems to be the standard of care versus a screening colonoscopy. A similar study with yearly FIT tests would be interesting to see. I suspect you might have a better compliance rate than the 42% seen in this study.

naasking 4y ago

Good discussion here, but I think the main message might get lost in the noise: * Colonoscopies reduce incidence of colon cancer but apparently not death from colon cancer. * This is probably because colon cancer therapies are good, so even if you get colon cancer your prognosis is good. * The take-away is not that colonoscopies reduce your chances of death, but that they reduce your chances of having to suffer colon cancer and subsequent therapies. That might still be a good trade-off.

rammy1234 4y ago

Title and end conclusion of the article are contradicting. Last paragraph says, "If you cannot take 2 days off, then you have other options. If you want to take test once in 10 years, Colonoscopy is the king". This means Colonoscopy is still the king if you can take 2 days off from your work ( which I believe most workers should be able to as this is important for one's life ). Not sure how this is beneficial for the readers of this article.

theptip 4y ago

I’m quite surprised in 2022 that news coverage is not mentioning the now well-known risks associated with colonoscopies. AIUI they are no longer recommended in the EU for routine screening because of the very high rate of dangerous side effects, on net increasing all cause mortality in the general population. The article here just looks at cancer mortality, which is not what anyone should care about. For more recent commentary, an example is https://blogs.scientificamerican.com/cross-check/why-i-wont-get-a-colonoscopy/ https://blogs.scientificamerican.com/cross-check/why-i-wont-...

noduerme 4y ago

Shouldn't this study properly be called "Effect of Offering Colonoscopy Screening on Risks..."? The headline result is based on the 18% decrease in CR cancer among people who were offered a colonoscopy. Of the people offered, only 42% actually got a colonoscopy. That means in the "colonoscopy group" 58% never even had one. Among those who did get one, there was a 31% decrease in CR cancer, and a 50% reduction in deaths from CR cancer. All the study really proves is that offering someone a colonoscopy isn't the same thing as giving them one.

alexjpb 4y ago

Irresponsible click bait title. If you are over 40,take a colonoscopy. I lost my brother (44) from colon cancer which could have been totally prevented. It was a very painful and depressing experience, multiple rounds of chemotherapy and surgeries that lasted over four years and sent his family into bankruptcy. He stopped eating solid foods weighing only 47 kilos and died from suffocation, pretty much liquid accumulating and pressing against his lungs until he could no longer breath. It's a slow and horrible dead that can be prevented with a simple one hour procedure done once every 5-10 years and in many cases 100% covered by insurance.

uslic001 4y ago

I would suggest reading the editorial also. Study has major limitations. From the doctor who wrote the editorial on Facebook Dr Jason Dominitz: "I'm honored to have been invited to write an editorial for the NEJM about the landmark NordICC study comparing screening colonoscopy to usual care (no screening) in Norway, Poland and Sweden. The NordICC results were somewhat disappointing in that colonoscopy only reduced colorectal cancer incidence by 18% at 10 years, with no significant mortality benefit. But only 42% of individuals who were invited to have a colonoscopy followed through. For those that did have colonoscopy, mortality was reduced by 50%. This study highlights the importance of adherence with screening. Also, we know that colonoscopy quality is variable and 29% of the endoscopists were not meeting quality benchmarks for polyp detection. So if you are getting a colonoscopy, ask your doctor what their "ADR" (adenoma detection rate) is. If they don't know, find another doctor to do your colonoscopy. The ADR should be well over 25% and, ideally, over 40%. " https://www.nejm.org/doi/full/10.1056/NEJMe2211595 https://www.nejm.org/doi/full/10.1056/NEJMe2211595 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375 https://www.nejm.org/doi/full/10.1056/NEJMoa2208375...