Most men with PSA levels of 4 ng/mL or below and who have been diagnosed with prostate cancer have low-risk disease yet undergo aggressive local treatment, a study found.
Some researchers have suggested lowering the 4 ng/mL threshold for biopsy, but, based on the new findings, investigators concluded: “Without the ability to distinguish indolent from aggressive cancers, lowering the biopsy threshold might increase the risk of overdiagnosis and overtreatment.”
The study, led by Grace L. Lu-Yao, PhD, of the Cancer Institute of New Jersey in New Brunswick, examined 2004-2006 data from the Surveillance, Epidemiology, and End Results (SEER) database, which contains the first available population-based collection of PSA levels and Gleason scores.
During the study period, 14% of prostate cancer cases were diagnosed in men who had PSA levels of 4 ng/mL or lower, the investigators reported in Archives of Internal Medicine (2010;170:1256-1261). Of these, 54% had low-risk disease (defined as clinical stage T2a or less, PSA level of 10 ng/mL or below, and a Gleason score of 6 or less). More than 75% of these patients underwent radical prostatectomy (RP) or radiotherapy (RT).
“The finding that men in low-risk groups were treated intensively raises the concern of overtreatment, especially among older patients,” the authors noted.
Compared with men who had non-screen-detected prostate cancer, men who had screen-detected disease and PSA values of 4 ng/mL or below were 49% and 39% more likely to receive RP and RT, respectively, and 33% less likely to have high-grade disease.
“These results underscore the fact that PSA level, the current biomarker, is not a sufficient basis for treatment decisions,” the researchers concluded.