Drs. Smith and Robertson share the common view that all prostate cancer, if left alone, will grow, spread, and kill. This is fortunately not the case. Some cancerous prostate tumors clearly grow and spread with devastating consequences, as both correspondents remind us, but most do not. The core of the difficulty is that clinicians cannot tell which is which at the time of diagnosis following a positive result on a screening test.

Autopsy studies show that approximately 30% of men at age 50 years, 50% of men at age 70 years, and almost all men by age 100 years have histologic cancer in the prostate. Thus, the tendency to recommend treatment for all men with a diagnosis of prostate cancer undoubtedly appropriately treats some but also harms those whose cancer could safely have been left alone. Even men who choose watchful waiting live with the awareness of having prostate cancer. In either case—treatment or watchful waiting—some men may suffer more harm than good from screening.

As with all screening tests, the USPSTF believes that individuals who are unwilling to undergo further diagnostic testing, treatment, and follow-up for positive test results should think carefully before having a prostate cancer screening test. Reasonable men may decide not to pursue such knowledge. Forcing men to learn they have prostate cancer through routine screening is, we believe, more paternalistic than offering them the opportunity to participate in an informed choice about whether to be screened in the first place.

Men now face a very difficult decision in balancing the potential benefit of screening, which may be enormous—avoidance of death from prostate cancer—against the potential harms, which are also significant and well documented. The USPSTF believes that the decision should be firmly in the hands of the patient. Unfortunately, we found the scientific evidence insufficient to recommend for or against routine screening. We hope that trials of screening now under way will provide better-quality evidence on which to base the decision.