In response to my note yesterday (see: When Routine Screening for Disease Has the Potential to Harm a Patient), a reader, Dr. Trent McBride, has submitted a thoughful comment. I thought that it would be useful to elevate it to the level of a note:
I am usually the first person to stand up and argue against the bias toward "doing" and "screening" we have in medicine; and before all of this came out, I would have guessed that doing PSAs was harmful; but after reading up on the big studies that led to this report, I am not so sure. Essentially, in the three [research studies] that I could find, the prostate cancer-specific mortality was decreased by 50% in the smallest, unchanged in the middle, and decreased by 20% in the largest (in the target age group: men < 70-75 yrs). Now, it is not entirely clear, but that looks like you could call that a real effect? If that is indeed the case, how in the world can the USPTF put it in the "D" category. Clearly, to me, if you read the definitions of the categories, it has to be a "C".
The lifetime risk of prostate cancer in 2.8%. A 20% reduction is roughly 0.5% risk. Is that worth the cost of testing/procedures and the risk of impotence/death? It is not obvious to me that it is; BUT, it is not obvious to me that it is not, either. I could imagine different patients making different trade-offs there. That, to me, is the essence of a "C" rating. "D" means: "few if any patients would benefit and make the above trade-off". And it seems to me that that is a leap. I am usually a fan of the USPTF, and there is a LOT left to be desired in the PSA, but I think they wiffed here.