Clinical Question: Is a four-year screening interval as effective as annual screening for prostate cancer?
Study Design: Randomized controlled trial (nonblinded)
Synopsis: More than 17,000 men 55 to 74 years of age were randomized to screening or no-screening groups. These study results describe the cohort of men being screened with rectal examinations, prostate-specific antigen (PSA) measurements, and ultrasonography (n = 8,350). After the first four years of follow-up, the investigators reported on the incidence of prostate cancer as confirmed by a review of the cancer registry. This could underestimate the true incidence of cancer.
During the first screening, 412 men were diagnosed with prostate cancer; only 25 more cases were detected after enrollment. This translates to an incidence of 21 cases per 1,000 person-years among men in the screening arm. Because the intervention group underwent ultrasonography, these data may not reflect what might be found if PSA measurements were to be used alone.
Bottom Line: The four-year rate of developing prostate cancer in screened men 55 to 74 years of age is fairly low. Although this study cannot tell us whether men are better or worse off as a result of screening, it suggests that for those men who choose to be screened, annual screening is unnecessary. Other, smaller studies similarly have found that men with low PSA levels do not need annual screening. (Level of Evidence: 2b)