Metformin Does Not Delay Progression on Active Surveillance for Low‑Risk Prostate Cancer — Unexpected Signal in Obesity

Highlight

– The Metformin Active Surveillance Trial (MAST), a multicenter, randomized, double‑blind, placebo‑controlled phase III trial, found no reduction in time to progression for men with low‑risk prostate cancer assigned to metformin versus placebo over 36 months (HR 1.09; 95% CI 0.79–1.52; P = .59).

– Negative biopsy rates at 36 months were numerically higher with metformin (41.0% vs 31.1%) but did not reach statistical significance (P = .181).