A drug commonly used to treat overactive bladder is proving effective in mitigating a debilitating side effect of prostate cancer treatment, according to results from a national clinical trial published this week. Oxybutynin significantly reduced the frequency and severity of hot flashes experienced by men undergoing androgen-deprivation therapy (ADT), researchers reported.
The study, led by the Alliance for Clinical Trials in Oncology and detailed in the Journal of Clinical Oncology, enrolled 88 men receiving ADT for prostate cancer at 15 academic and community cancer centers. Final analysis included 81 participants who reported an average of 10.1 hot flashes per day. Participants were randomly assigned to receive either oxybutynin at 2.5 mg or 5 mg twice daily, or a placebo, for six weeks.
Men receiving the placebo experienced an average reduction of 2.15 hot flashes per day. Those taking 2.5 mg of oxybutynin twice daily reported reductions of 4.77 hot flashes per day (P = .02), even as those on the 5 mg dose experienced a reduction of 6.89 hot flashes per day (P < .001). Daily hot flash scores also improved, with the 5 mg oxybutynin group showing the most substantial decrease, at 13.95 points (P = .002), compared to a 4.85-point reduction in the placebo group.
“Oxybutynin demonstrated clear and clinically meaningful improvements in both hot flash frequency and quality of life for men undergoing hormone therapy for prostate cancer,” said Bradley J. Stish, MD, the study’s lead investigator and a radiation oncologist at the Mayo Clinic. “These results provide strong support for its employ as an effective management option for this challenging and often overlooked side effect of prostate cancer treatment.”
Androgen-deprivation therapy, while effective in slowing the progression of prostate cancer by reducing testosterone levels, frequently causes hot flashes in up to 80% of patients. These hot flashes can lead to fatigue, sleep disturbances, and a diminished quality of life, sometimes prompting patients to discontinue ADT altogether. The trial also assessed changes in Hot Flash-Related Daily Interference Scale (HFRDIS) scores, finding improvements of 14.2 and 20.7 points in the 2.5 mg and 5 mg oxybutynin arms, respectively, compared to a 3.1-point improvement with placebo.
Researchers reported no treatment-related grade 3 or higher adverse events occurred during the trial. The average age of participants was 68.5 years old. The study’s findings, published January 26, 2026, suggest a readily available and well-tolerated option for managing ADT-associated hot flashes.
