Time to an undetectable prostate‐specific antigen (PSA) after androgen suppression therapy for postoperative or postradiation PSA recurrence and prostate cancer‐specific mortality

BACKGROUND: For men receiving androgen-suppression therapy (AST) for a rising postoperative or postradiation prostate-specific antigen (PSA) recurrence, whether the time to an undetectable (u) PSA was significantly associated with prostate cancer-specific mortality (PCSM) was evaluated. METHODS: The study cohort comprised 585 men with a rising PSA and negative bone scan after surgery (n = 415) or radiation therapy (n = 170) that were treated with AST and achieved a uPSA. Gray's regression was used to evaluate whether the time to a uPSA after AST was significantly associated with the time to PCSM after the uPSA adjusting for known prognostic factors. RESULTS: The median time (interquartile range) to achieve a uPSA was 4.6 (range, 2.8-7.8) months. There were 23 deaths, 4 of which were from prostate cancer. An increasing time to a uPSA (adjusted hazard ratio [HR]: 9.2, 95% confidence interval [CI]: 3.8, 22.1; P < .0001), a decreasing PSA doubling time (DT) (HR: 0.58, 95% CI: 0.43, 0.80; P = .0007), and Gleason score 8 to 10 cancers (HR: 8.6, 95% CI: 1.04, 77; P = .05) were significantly associated with a shorter time to PCSM. CONCLUSIONS: Despite achieving a uPSA after AST, the risk of PCSM increased significantly as the time to the uPSA lengthens, especially in men with a short pre-AST PSA DT and high-grade prostate cancer. These men should be considered for randomized studies evaluating immediate vs delayed chemotherapy after the achievement of the uPSA.