In the British Medical Journal this week, readers respond to a study that appeared in the journal in March, which suggested that there is no difference in outcome for men who are regularly screened for prostate cancer versus those who are not. Dutch urologist Fritz Schroder writes in a letter that the study had "major shortcomings." Among them, he says, the group of men randomized to screening was very small, and of the 85 prostate cancers diagnosed in screening, 42 were detected as interval cancers, which implies "ineffective screening" during the first two screening rounds. The study's authors respond, saying that although the number of men in the screening group is much smaller than other studies, the long follow-up — 20 years — gives the study statistical power. In addition, the authors write, although the many interval cancers had a large impact on the outcome of the study, screening methods today are much more effective than they were when the study was conducted.
In another letter, the University of Massachusetts Medical School's Jesse Aronowitz questions the study's conclusion that screening offers little benefit. A quarter of the men randomized to the screening cohort didn't attend and two thirds of the attendees weren't invited for a second prostate specific antigen determination because of their age, and Aronowitz questions whether a single PSA test be considered a screening program. Also, only a quarter of the men diagnosed with prostate cancer in the screening cohort were treated with "curative intent," and about half of the men in the entire study died of their disease. "An equally valid reason for the dismal prostate cancer survival among these men is that they were underscreened and undertreated," he adds. The study's authors reply that most of the men attended at least two screening rounds and that the high mortality in the screening group is probably explained by the low percentage of men undergoing "radical treatment."