5α-reductase inhibitors and the risk of grade reclassification for men with long-term follow-up on active surveillance for prostate cancer.

Abstract

92 Background: The role of 5α-reductase inhibitors (5-ARIs) in prostatic diseases remains controversial because of an FDA black box label. We have previously published on the impact of 5-ARIs in men managed with active surveillance (AS), demonstrating their protective effect against progression. However, the long-term safety of 5-ARIs in the setting of AS has never been described, thus we sought to assess this. Methods: This is a single-institution, prospectively maintained, retrospective cohort study comparing men taking a 5-ARI versus no 5-ARI while on AS for PCa. Pathologic progression was evaluated and defined as Gleason score > 6, maximum core involvement > 50%, or more than 3 cores positive on a follow-up prostate biopsy. Time dependent covariate analysis to account for time on AS but not on 5-ARI was conducted to diminish the likelihood of overestimating the benefit. To account for differences in prostate volume at baseline between 5-ARI and non-5-ARI groups sensitivity analyses were performed, restricting men in the non-5-ARI group to those with larger glands (volume > 40 ml). Kaplan-Meier analyses were conducted along with multivariable Cox proportional hazard regression modeling for predictors of pathologic progression. Results: The original cohort of 288 men on AS were analyzed. The median follow-up was 61.2 months (IQR: 29.8-95.24) with 124 men (43%) experiencing pathologic progression and 119 men (41.3%) abandoning AS. Men taking a 5-ARI experienced a lower rate of pathologic progression (24.3% vs 49.1%; p < 0.001) and were less likely to abandon AS (25.7% vs 46.3%; p = 0.002). On multivariable Cox proportional hazards analysis, lack of 5-ARI use was most strongly associated with pathologic progression (HR: 2.56; 95% confidence interval, 1.32-5.02). Sensitivity analyses done to account for gland size demonstrated that lack of 5-ARI use was still predictive of progression (HR: 2.76; CI, 1.45–5.25; p = 0.002). Importantly, 5-ARI use was not associated with increased risk of high-grade prostate cancer. Conclusions: 5-ARIs were associated with a significantly lower rate of pathologic progression and abandonment of AS in men with median follow-up of 5 years.