In March 2009, the New England Journal of Medicine, one of the most cited and prestigious sources of medical information, published two very important contributions to our understanding of prostate cancer. These articles address the value of screening for this disease. In the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, approximately 76,000 American men were randomly assigned to participate in one of two groups: early detection of prostate cancer using annual prostate specific antigen (PSA) and digital rectal examination screening, or no screening (the control arm). At the end of 10 years, there was no difference in deaths from prostate cancer between the groups. Similarly, the European Randomized Study of Screening for Prostate Cancer (ERSPC) randomized approximately 160,000 men to either screening with PSA or no screening. At the end of nine years, this study showed a significant 20% decrease in deaths from prostate cancer in the screened group. To accomplish this apparently beneficial result, over 1400 men would need to be screened and an additional 48 cases would have to be treated to prevent a single prostate cancer death.
These apparently contradictory results may not, in fact, be that different. Both of these major contributions are now the subject of intense scrutiny and varying interpretation. Neither study is without methodologic problems. The final results are not in for either of these trials, because of many outstanding issues including screening criteria, contamination of the control arm (by screening) and duration of follow-up. Proponents of screening will continue to find ample support for this strategy from these trials, while opponents will equally feel vindicated in their views.
One thing is abundantly clear, however — the decision to be screened or treated will remain a very personal one, which men can only arrive at with as much knowledge and support as is available. Read this edition of Our Voice to be better informed.
