The Effect of Prostate Volume and 5-Alpha Reductase Inhibitor Use on Grade Progression and Treatment Decisions in Patients with Prostate Cancer on Active Surveillance

PURPOSE: To evaluate the impact of prostate volume and 5-alpha reductase inhibitor (5-ARI) use on oncologic outcomes and benign prostatic hyperplasia (BPH) management among patients undergoing active surveillance (AS) for low-grade prostate cancer (PCa). MATERIALS AND METHODS: We retrospectively reviewed patients with Grade Group 1 (GG1) disease on AS. Multivariable extended Cox models examined the associations between prostate volume (at confirmatory biopsy), 5-ARI use, and three outcomes: grade progression (GP) on biopsy (to ≥GG2 and extreme GP to ≥GG3), receipt of a bladder outlet procedure, and definitive PCa treatment. RESULTS: Among 1,938 patients, 14% had volumes <30 cc, 73% had 30-80 cc, and 14% had >80 cc. Patients with prostate volumes >80 cc were more likely to undergo bladder outlet procedures (p<0.001). On multivariable analysis, increasing prostate volume was associated with decreased rates of GP (HR 0.89, 95% CI 0.85-0.93, p<0.001) and PCa treatment (HR 0.91, 95% CI 0.88-0.95, p<0.001) per 10 cc. 5-ARI use (per year) was associated with significant reductions in GP (HR 0.80, 95% CI 0.72-0.89, p<0.001), extreme GP (HR 0.84, 95% CI 0.73-0.97, p = 0.02), and PCa treatment (HR 0.53, 95% CI 0.41-0.67, p<0.001). CONCLUSIONS: Among patients with low-grade PCa on AS, increased prostate volume was associated with lower risks of GP and receipt of definitive PCa treatment. BPH symptoms can safely be managed on AS, including with 5-ARIs, which were associated with lower risks of GP and progression to definitive treatment in this cohort.