Time to Benefit of Androgen Deprivation Therapy in Patients With Localized Prostate Cancer Undergoing Radiotherapy.

Purpose: Combining radiotherapy with androgen deprivation therapy (ADT) is recommended for localized prostate cancer. However, the time required for significant therapeutic benefits is not well quantified. This study aims to determine the time to benefit (TTB) of ADT in these patients.

Methods: We systematically searched PubMed, Scopus, Embase, and Cochrane databases for randomized clinical trials that compared definitive radiotherapy with or without ADT in localized prostate cancer. The primary end point was all-cause mortality. We reconstructed individual patient survival data and calculated TTB using Weibull survival curves, the frequentist method, and the delta method.

Results: Eight trials with 6,839 participants were included, with more than 80% of them being patients with intermediate- or high-risk prostate cancer. For patients adding ADT to radiotherapy, it took 7.46 (95% CI, 2.53 to 22.00), 11.36 (95% CI, 4.61 to 28.03), 19.97 (95% CI, 10.03 to 39.78), and 30.90 months (95% CI, 17.90 to 53.36) to prevent one case of all-cause mortality per 1,000, 500, 200, and 100 patients, respectively. To prevent one case of prostate cancer-specific mortality, local progression, distant metastasis, and biochemical failure per 100 patients, it required 40.58 (95% CI, 30.20 to 54.53), 10.92 (95% CI, 6.03 to 19.79), 11.36 (95% CI, 6.55 to 19.69), and 7.80 months (95% CI, 5.14 to 11.83), respectively.

Conclusion: Adding ADT to radiotherapy provides rapid clinical benefits for patients with intermediate- and high-risk localized prostate cancer. Patients with an expected lifespan over 30 months may benefit from this treatment.