Men on active surveillance long-term who take 5-alpha-reductase inhibitors (5-ARIs) have a lower rate of prostate cancer (PCa) progression than those not taking the drugs. Users also are less likely to quit active surveillance. Investigators presented the study findings on Thursday at the 2016 Genitourinary Cancers Symposium in San Francisco.
The results corroborate previous research by the investigators demonstrating a protective effect of 5-ARIs against PCa progression in the short term.
For the latest study, investigators led by Antonio Finelli, MD, of the University of Toronto, retrospectively studied 288 men on active surveillance for PCa at a single institution. Over a median follow-up of 61.2 months, 124 men (43%) experienced pathologic progression, defined as Gleason score greater than 6, maximum core involvement greater than 50%, or more than 3 cores positive on a follow-up prostate biopsy. A total of 119 men (41.3%) quit the active surveillance program.
Men taking a 5-ARI experienced a lower rate of pathologic progression (24.3% vs. 49.1%) and were less likely to abandon active surveillance compared with non-users (25.7% vs 46.3%). On multivariable analysis, not taking a 5-ARI was associated with a nearly 2.6 times increased risk of pathologic progression compared with 5-ARI use. When investigators accounted for prostate gland size, non-use of 5-ARIs was associated with an approximately 2.8 times increased risk of progression. The researchers accounted for time on active surveillance.
Importantly, despite an FDA warning on the drug label, the investigators reported finding no increased risk of high-grade prostate cancer with 5-ARI use.