I drafted the following modest post before the U.S. Preventive Services Task Force USPSTF released its latest recommendation on the PSA test, which does not deviate from its draft recommendation. Sharon Begley has done fantastic reporting on the issue. And you’ll find a good post at The 141.
In a NEJM editorial, Anthony Miller tries to make sense of the contradictory results from two recent studies of the PSA test.
After 11 years of follow-up in the European Randomized Study of Screening for Prostate Cancer (ERSPC), Schröder et al. report in this issue of the Journal that there has been little change in the apparent benefit of screening men for levels of prostate-specific antigen (PSA), as compared with an earlier report. Both studies showed a relative reduction of 21% in the rate of death from prostate cancer in the screening group, as compared with the control group. This reduction was achieved after considerable use of resources: in order to prevent one death from prostate cancer at 11 years of follow-up, 1055 men would need to be invited for screening and 37 cancers would need to be detected. Only in the Netherlands and Sweden was the between-group difference statistically significant . No significant between-group difference in all-cause mortality was noted.
In a similar update on prostate-cancer mortality in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial investigators reported no significant change from the findings of the earlier study. Thus, regarding PSA screening, the negative findings of the PLCO trial and the positive findings of the ERSPC are unchanged. [...]
What the PLCO trial seems to show is that adding organized screening to opportunistic screening will result in no benefit and many adverse effects. These effects include false positive screening tests, unnecessary biopsies, overdiagnosis, and impaired quality of life.
In much of the rest of the editorial, Miller explains some of the differences between the two studies that might explain the divergence of results. In light of these differences, he concludes,
We are left with an unsatisfactory situation, in which many practitioners will think there are insufficient data to recommend abandoning PSA screening for prostate cancer. However, the findings of the PLCO trial are more applicable to the situation in the United States, since the ERSPC was conducted in a largely PSA-naive population. Therefore, an intensification of PSA screening would be unwise, and I think it would be advisable to follow the  recommendations of the U.S. Preventive Services Task Force.