Oxybutynin Demonstrates Significant Efficacy in Reducing Hot Flashes for Prostate Cancer Patients on Hormone Therapy
Key Insights
A Phase II randomized, double-blind, placebo-controlled trial found that oxybutynin, commonly used for overactive bladder, significantly reduces hot flashes in men receiving androgen-deprivation therapy for prostate cancer.
The study showed dose-dependent improvements, with the 5 mg twice daily group experiencing 6.89 fewer hot flashes per day and a 13.95-point reduction in severity scores compared to placebo.
Seventy-nine percent of patients receiving the higher dose achieved at least a 50% reduction in hot flash scores, compared to only 32% in the placebo group.
A national clinical trial led by the Alliance for Clinical Trials in Oncology has demonstrated that oxybutynin, a medication traditionally used to treat overactive bladder symptoms, provides significant relief from hot flashes in men receiving hormone therapy for prostate cancer. The findings, published in the Journal of Clinical Oncology, offer a promising new treatment option for a side effect that affects up to 80% of patients undergoing androgen-deprivation therapy (ADT).
Clinical Trial Results Show Dose-Dependent Benefits
The Phase II randomized, double-blind, placebo-controlled trial (Alliance A222001) evaluated two doses of oxybutynin against placebo over a six-week treatment period. The study enrolled 88 men from 15 academic and community cancer centers, with 81 participants eligible for final analysis. The average age of participants was 68.5 years.
Both doses of oxybutynin demonstrated substantial improvements compared to placebo. Men receiving placebo experienced an average reduction of 2.15 hot flashes per day and a 4.85-point drop in daily hot flash severity scores. In contrast, those taking 2.5 mg of oxybutynin twice daily reported reductions of 4.77 hot flashes per day and a 9.94-point decrease in severity. The higher dose group (5 mg twice daily) experienced the most significant improvements, with 6.89 fewer hot flashes per day and a 13.95-point reduction in severity scores.
Rapid Onset and Sustained Efficacy
The therapeutic benefits of oxybutynin manifested quickly, often during the first week of treatment, and were sustained throughout the entire study period. The proportion of patients achieving at least a 50% reduction in hot flash scores was markedly higher with oxybutynin treatment: 57% in the 2.5 mg group and 79% in the 5 mg group, compared with only 32% taking placebo.
"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 radiation oncologist at Mayo Clinic. "These results provide strong support for its use as an effective management option for this challenging and often overlooked side effect of prostate cancer treatment."
Addressing an Unmet Medical Need
Androgen-deprivation therapy remains an effective treatment against prostate cancer by lowering male hormones like testosterone that fuel cancer cell growth. However, the therapy's side effects, particularly hot flashes, create significant quality-of-life challenges. Hot flashes from ADT lead to fatigue, sleep disturbances, and reduced quality of life, often causing patients to discontinue treatment due to these adverse effects.
Safety Profile and Tolerability
The treatment was well-tolerated overall, with dry mouth reported as the most common side effect. This favorable safety profile, combined with the drug's established use in treating overactive bladder symptoms, supports its potential adoption for managing hot flashes in prostate cancer patients.
"These results are incredibly encouraging," Dr. Stish noted. "Men with hot flashes from hormone therapy now have another therapeutic option available to help reduce their symptom burden. Future research will look to further our understanding of hot flash therapy options in this patient population."
The study was supported by the National Cancer Institute of the National Institutes of Health and involved investigators from multiple institutions including Mayo Clinic, Georgetown-Lombardi Comprehensive Cancer Center, Yale University School of Medicine, and The Ohio State University, among others.