6 ms·

It's good to be publishing stats like this so that the psychological harm of false positives is lower. It's scary to get a false positive. However, in my opini

It's good to be publishing stats like this so that the psychological harm of false positives is lower. It's scary to get a false positive. However, in my opinion, there has been a systemic resistance to screening because of statistics like this, and that is misguided. This is not the right number to use for determining whether or not screening is useful. A 3D mammogram will have false positives, yes. And some women will need to either get an uneccesary ultrasound (annoying, but not harmful) or worse, an uneccessary tissue sample (biopsy). This type of biopsy is done with a needle and is certainly uncomfortable, but carries little to no risk. This is all true. But it needs to be balanced against the fact that catching cancer early gives you an immensely better chance of surviving. The right numbers to look at are more like: How much does a screening program reduce overall mortality rates? How much does the screening program reduce breast cancer mortality rate? What are the impacts of this in terms of QALY (quality adjusted life years)? What are the impacts of the false positives in quality adjusted life years? I believe on balance the answer to these questions is that screening for breast cancer is on the whole beneficial. Here is one example study https://pubmed.ncbi.nlm.nih.gov/31098856/ https://pubmed.ncbi.nlm.nih.gov/31098856/ Now the question is, how will 3D affect these questions? That is as of yet unanswered as far as I know but we shouldn't let numbers like this influence the conversation prematurely.

Aulig 4y ago
You're totally right. However, the study you link does not discuss mortality while taking overdiagnosis into account from what I can tell. Other studies (first one I found: https://pubs.rsna.org/doi/full/10.1148/radiol.11110210 https://pubs.rsna.org/doi/full/10.1148/radiol.11110210 ) can't confirm a significant reduction in mortality.
- dontreact 4y ago
  Yeah I just linked that study because it was looking at QALY which is an aggregate metric so it should in some sense take into account the effects of overdiagnosis even if overdiagnosis is not explicitly handled. Here is another study looking at all-cause mortality, which again does implicitly handle overdiagnosis. https://www.ajronline.org/doi/full/10.2214/AJR.14.12666 https://www.ajronline.org/doi/full/10.2214/AJR.14.12666
aeternum 4y ago
Yes, the problem is mostly one of presentation. To most people a positive test means it is likely they have it, which is often a statistically invalid conclusion. We should instead present it as 'you currently have breast cancer with 13% probability' (population avg with no tests), a positive test means you have it with 25% probability, a negative test with 3% probability. That makes the test a lot less scary, after all you're only gaining 10% certainty either direction.
- conductr 4y ago
  I don't believe we should present it as a statistics. Most people would not understand or feel comforted by that explanation. 'you currently have breast cancer' is all the person will see and the numbers and implications of will be lost on them. I feel like this is where bedside manor comes into play and the human component of being a physician. Any doctor ordering a 3D mammogram, then receiving a positive result, should communicate to their patient that imaging is just a screening tool and not diagnostic. Many doctors will not even use the word "Positive" in the test result conversation. They'll use vague wording like, "we did happen to see something we'd like to investigate further to be sure, it's really hard to see exactly what's going on in your body on a camera so while I was hoping to avoid it I do believe a biopsy should be the next step". Yes, a biopsy is now warranted, but the patient should try to keep up their spirits high and not stress to much at this point. The biopsy will tell more information about what is going on inside the body and we can come up with a plan for whatever that is once we know more. It's natural/unavoidable for the patient to be worried/anxious but should not yet be scared and that is best conveyed in a human interaction with a caring physician.

Aulig 4y ago

You're totally right. However, the study you link does not discuss mortality while taking overdiagnosis into account from what I can tell. Other studies (first one I found: https://pubs.rsna.org/doi/full/10.1148/radiol.11110210 https://pubs.rsna.org/doi/full/10.1148/radiol.11110210 ) can't confirm a significant reduction in mortality.

dontreact 4y ago
Yeah I just linked that study because it was looking at QALY which is an aggregate metric so it should in some sense take into account the effects of overdiagnosis even if overdiagnosis is not explicitly handled. Here is another study looking at all-cause mortality, which again does implicitly handle overdiagnosis. https://www.ajronline.org/doi/full/10.2214/AJR.14.12666 https://www.ajronline.org/doi/full/10.2214/AJR.14.12666

aeternum 4y ago

Yes, the problem is mostly one of presentation. To most people a positive test means it is likely they have it, which is often a statistically invalid conclusion. We should instead present it as 'you currently have breast cancer with 13% probability' (population avg with no tests), a positive test means you have it with 25% probability, a negative test with 3% probability. That makes the test a lot less scary, after all you're only gaining 10% certainty either direction.

conductr 4y ago
I don't believe we should present it as a statistics. Most people would not understand or feel comforted by that explanation. 'you currently have breast cancer' is all the person will see and the numbers and implications of will be lost on them. I feel like this is where bedside manor comes into play and the human component of being a physician. Any doctor ordering a 3D mammogram, then receiving a positive result, should communicate to their patient that imaging is just a screening tool and not diagnostic. Many doctors will not even use the word "Positive" in the test result conversation. They'll use vague wording like, "we did happen to see something we'd like to investigate further to be sure, it's really hard to see exactly what's going on in your body on a camera so while I was hoping to avoid it I do believe a biopsy should be the next step". Yes, a biopsy is now warranted, but the patient should try to keep up their spirits high and not stress to much at this point. The biopsy will tell more information about what is going on inside the body and we can come up with a plan for whatever that is once we know more. It's natural/unavoidable for the patient to be worried/anxious but should not yet be scared and that is best conveyed in a human interaction with a caring physician.