Well, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) was done in the US and the European Randomized Study of Screening for Prostate Cancer (ERSPC) was done in Europe. The PSA cutoff and frequency of screening was higher in the US study.

But they differed in one way that isn't readily apparent from this table. In the US, during the PLCO trial, individuals in the "no screening" arm were getting screened anyway as part of their usual care. In fact, some estimates suggest as many as 90% of the individuals in the no-screening arm had at least one PSA test during the trial. Maybe it's not the differences between Europe and the US that led to these disparate results – maybe it's because the intensity of screening was so much higher in the control group in the US study.

Enter Ruth Etzioni and her team from the Fred Hutch Cancer Center with this article, appearing in the Annals of Internal Medicine.