Randomized study of oxybutynin versus placebo for hot flashes in patients receiving androgen deprivation therapy for prostate cancer

The multicenter Alliance S222001 trial randomized patients receiving androgen deprivation therapy (ADT) for prostate cancer with at least 28 hot flashes per week to receive oxybutynin 2.5 mg twice daily, oxybutynin 5 mg twice daily, or matching placebo for 6 weeks. The primary endpoint was change in patient-reported hot flashes scores since baseline at 6 weeks. The study enrolled 81 patients eligible for analysis, reporting baseline average 10.1 ± 5.55 hot flashes per day and an average daily hot flash score of 18.2 ± 13.55. At 6 weeks, on average, patients in the placebo group, 2.5 mg oxybutynin group, and 5 mg oxybutynin group had reductions in hot flashes per day of 2.15, 4.77 (p=0.02), and 6.89 (p<0.001), respectively, whereas daily hot flash scores reduced by and average of 4.85, 9.94 (p=0.07), and 13.95 (p=0.002) points, respectively, and Hot Flash-Related Daily Interference Scale scores improved by 3.1 points, 14.2 points (p=0.042) and 20.7 points (pxtagstartz0.01). No treatment-related grade ≥ 3 adverse events occurred. The authors conclude that oxybutynin is superior to placebo for the management of ADT-associated hot flashes in men with prostate cancer.