That's all nice but we used to recommend systematic PSA screening for all males over 50. We later realized that there was a lot of false positives and that the

That's all nice but we used to recommend systematic PSA screening for all males over 50. We later realized that there was a lot of false positives and that the intervention often brought more risks than it cured actual cancers. So it's only recommended for patients with risk factors. Now, consider the GP who has healthy 50yo, does a PSA anyway and it's positive. The GP could still decide not to act. But the patient is not so likely not to do anything. Or even understand the odds. At that point, if the patient dies, the GP is likely to get sued because he should have acted. Even if over all of his patients, not acting was more efficient. If the GP decides to act, however, regardless of whether the patient survives, he won't be blamed for it. So doctors have a nasty incentive to act.