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To clarify the Hacker News title, the article is talking specifically about prostate-specific antigen (PSA) screening, which is already known to be of uncertain

To clarify the Hacker News title, the article is talking specifically about prostate-specific antigen (PSA) screening, which is already known to be of uncertain medical value except in some very specific situations. As the discoverer of PSA said, "I never dreamed that my discovery four decades ago would lead to such a profit-driven public health disaster. The medical community must confront reality and stop the inappropriate use of P.S.A. screening. Doing so would save billions of dollars and rescue millions of men from unnecessary, debilitating treatments." http://www.nytimes.com/2010/03/10/opinion/10Ablin.html http://www.nytimes.com/2010/03/10/opinion/10Ablin.html There are other more promising methods of prostate cancer screening in development that will hopefully be able to do better in the future.

carbocation 15y ago
Yes, the HN title was only intended to capture what I saw as the most salient result of the study, whose actual title is "Prostate-Cancer Mortality at 11 Years of Follow-up". I'd be happy to change the title if this one is considered too editorializing.
bermanoid 15y ago
From the link you posted: "last month, the American Cancer Society urged more caution in using the test" It's a very sad state of affairs when a test that unambiguously offers some statistical utility (speaking as a Bayesian, any test is useful if we do the right things with the results, this is quite literally a provable theorem of decision theory) is potentially problematic because we aren't properly evaluating what to do when we get the results. I can't blame patients here, they're not the experts; it's doctors (and perhaps more fairly, the entire medical research industry) that need to wise the fuck up and realize that they're acting as statistical dilettantes in a field where they're putting patients lives at risk because they don't understand math very well. Yes, even a test that only detects ~3% of cancers should be useful; but this requires that doctors completely understand what it means both to see a positive and a negative result, and don't overreact when they see either one. If this was a matter of just weighing the costs of having tests done versus the benefits of getting the results, it would be one thing. But it's not. People actually end up suffering and spending great amounts of money just because they did "the right thing" and had tests run, and then listened to the doctors' advice afterwards. Once more with feeling: after discounting for the cost of the test, there is no test that should be of negative value for a rational agent to take. The results should always be used in a way that, in general, increases the welfare of the people taking the test. If this is not the case in medicine, then they're doing something seriously wrong mathematically speaking, and this is a very bad thing that should be a high priority to fix.
- Sniffnoy 15y ago
  Unless taking the test has a cost in and of itself -- such as if it requires surgery, so that the risk of something going wrong during testing might outweigh the information gained if the condition being tested for is rare.
  - bermanoid 15y ago
    Yup, definitely, I should have made that more clear than it was (I did mention "after discounting for the cost of the test", but it wasn't as obvious as it should have been). Test costs have to be weighed against benefits, but that whole process involves a lot more statistical sophistication than is typically applied in practiced medicine. Researchers are slightly better, though it's fairly common even for them to make hideous statistical mistakes, which is a real problem in the field. IMO, if pre-med requirements included a bit more statistics and a bit less biology, we'd all be better off...
    - Sniffnoy 15y ago
      Ah, I missed that you included that.
- mikenuman 15y ago
  This is a very difficult area. Firstly, these consults are never as easy or logical in real life. If you think doctors don't understand Bayesian probabilities then how well do you think patients do? Decision making when screen positive results occur, with appropriate perspective, is virtually impossible for patients. I've lost count of the procedures I've done for incidental findings found with screening, which we KNOW are benign and will remain benign. Unfortunately, despite very strong reassurance, patients generally want these incidentalomas removed. Secondly, unless your positive screening test can be dealt with.... a) by a procedure that has zero risk of complications and b) in a way where no stress is engendered while waiting for definitive results and) the costs of (screening + treatment) could not be more effectively spent elsewhere ...then there will ALWAYS be negative sequelae with screening. Therefore these negatives need to be assessed in a real world RCT of sufficient size and with maximal control of bias, to make sure they don't outweigh the positives. Your perfect world of logical patients balancing pre- and post-test probabilities, and acting accordingly doesn't exist.

carbocation 15y ago

Yes, the HN title was only intended to capture what I saw as the most salient result of the study, whose actual title is "Prostate-Cancer Mortality at 11 Years of Follow-up". I'd be happy to change the title if this one is considered too editorializing.

bermanoid 15y ago

From the link you posted: "last month, the American Cancer Society urged more caution in using the test" It's a very sad state of affairs when a test that unambiguously offers some statistical utility (speaking as a Bayesian, any test is useful if we do the right things with the results, this is quite literally a provable theorem of decision theory) is potentially problematic because we aren't properly evaluating what to do when we get the results. I can't blame patients here, they're not the experts; it's doctors (and perhaps more fairly, the entire medical research industry) that need to wise the fuck up and realize that they're acting as statistical dilettantes in a field where they're putting patients lives at risk because they don't understand math very well. Yes, even a test that only detects ~3% of cancers should be useful; but this requires that doctors completely understand what it means both to see a positive and a negative result, and don't overreact when they see either one. If this was a matter of just weighing the costs of having tests done versus the benefits of getting the results, it would be one thing. But it's not. People actually end up suffering and spending great amounts of money just because they did "the right thing" and had tests run, and then listened to the doctors' advice afterwards. Once more with feeling: after discounting for the cost of the test, there is no test that should be of negative value for a rational agent to take. The results should always be used in a way that, in general, increases the welfare of the people taking the test. If this is not the case in medicine, then they're doing something seriously wrong mathematically speaking, and this is a very bad thing that should be a high priority to fix.

Sniffnoy 15y ago
Unless taking the test has a cost in and of itself -- such as if it requires surgery, so that the risk of something going wrong during testing might outweigh the information gained if the condition being tested for is rare.
- bermanoid 15y ago
  Yup, definitely, I should have made that more clear than it was (I did mention "after discounting for the cost of the test", but it wasn't as obvious as it should have been). Test costs have to be weighed against benefits, but that whole process involves a lot more statistical sophistication than is typically applied in practiced medicine. Researchers are slightly better, though it's fairly common even for them to make hideous statistical mistakes, which is a real problem in the field. IMO, if pre-med requirements included a bit more statistics and a bit less biology, we'd all be better off...
  - Sniffnoy 15y ago
    Ah, I missed that you included that.
mikenuman 15y ago
This is a very difficult area. Firstly, these consults are never as easy or logical in real life. If you think doctors don't understand Bayesian probabilities then how well do you think patients do? Decision making when screen positive results occur, with appropriate perspective, is virtually impossible for patients. I've lost count of the procedures I've done for incidental findings found with screening, which we KNOW are benign and will remain benign. Unfortunately, despite very strong reassurance, patients generally want these incidentalomas removed. Secondly, unless your positive screening test can be dealt with.... a) by a procedure that has zero risk of complications and b) in a way where no stress is engendered while waiting for definitive results and) the costs of (screening + treatment) could not be more effectively spent elsewhere ...then there will ALWAYS be negative sequelae with screening. Therefore these negatives need to be assessed in a real world RCT of sufficient size and with maximal control of bias, to make sure they don't outweigh the positives. Your perfect world of logical patients balancing pre- and post-test probabilities, and acting accordingly doesn't exist.