But notice that pretty much every screen has a false positive rate. So some percentage of the healthy people screened are going to be incorrectly told that thei

But notice that pretty much every screen has a false positive rate. So some percentage of the healthy people screened are going to be incorrectly told that their sick, and therefore get treated for an illness they don't have. The more people you screen, the more that's going to happen. And when the treatments are things like surgery, chemotherapy, radiation, etc, that's a pretty big deal. Also, not everything that shows up in a screen was going to be a problem. It could be that it might have never been a problem. Quoting Wikipedia about mammography: >> While this ability to detect such very early breast malignancies is at the heart of claims that screening mammography can improve survival from breast cancer, it is also controversial. This is because a very large proportion of such cases will not progress to kill the patient, and thus mammography cannot be genuinely claimed to have saved any lives in such cases; in fact, it would lead to increased sickness and unnecessary surgery for such patients. https://en.wikipedia.org/wiki/Breast_cancer_screening#Criticisms https://en.wikipedia.org/wiki/Breast_cancer_screening#Critic...