Monday, May 21, 2012

Cancer screening in men: flexible sigmoidoscopy works, PSA does not

The cover article of AFP's May 15th issue reviews evidence-based components of the adult well male examination. Among the recommended tests for men (and women) age 50 years and older is screening for colorectal cancer via periodic fecal occult blood testing, flexible sigmoidoscopy, or colonoscopy. Yesterday, the lead researchers of the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial reported in the New England Journal of Medicine that flexible sigmoidoscopy every 3 to 5 years reduced deaths from colorectal cancer by 26 percent, a very impressive result given that nearly half of the participants in the control group were also screened at least once.

Today, the U.S. Preventive Services Task Force finalized its provisional recommendation to assign PSA-based screening for prostate cancer a "D" (don't do) grade in men of any age. The USPSTF's conclusion from five randomized, controlled trials that PSA-based screening produces no health benefits is consistent with a Cochrane for Clinicians review that AFP published more than a year ago. Evaluating the entire body of evidence, the Task Force concluded:

The reduction in prostate cancer mortality after 10 to 14 years [from PSA-based screening] is, at most, very small, even for men in what seems to be the optimal age range of 55 to 69 years. ... In contrast, the harms associated with the diagnosis and treatment of screen-detected cancer are common, occur early, often persist, and include a small but real risk for premature death. ...The inevitability of overdiagnosis and overtreatment of prostate cancer as a result of screening means that many men will experience the adverse effects of diagnosis and treatment of a disease that would have remained asymptomatic throughout their lives. ... The USPSTF concludes that there is moderate certainty that the benefits of PSA-based screening for prostate cancer do not outweigh the harms.

Few family physicians still perform screening flexible sigmoidoscopies, and PSA is one of the most commonly ordered blood tests in men over 50. How long will take to change both of these practices to reflect the best evidence?