A recent national clinical trial has found that oxybutynin, a medication typically used to treat overactive bladder, can significantly reduce hot flashes in men undergoing hormone therapy for prostate cancer. The findings from the Alliance A222001 study were published in the Journal of Clinical Oncology.
Androgen-deprivation therapy (ADT) is commonly used to lower testosterone and other male hormones that help fuel prostate cancer cells. However, up to 80 percent of men on ADT experience hot flashes, which can lead to fatigue, sleep problems, and a reduced quality of life. These side effects sometimes cause patients to stop their treatment.
The Phase II trial was randomized, double-blind, and placebo-controlled. It tested two doses of oxybutynin—2.5 mg twice daily and 5 mg twice daily—against a placebo over six weeks. The study enrolled 88 men from 15 academic and community cancer centers across the United States; 81 participants were included in the final analysis with an average age of 68.5 years.
Results showed that both doses of oxybutynin led to greater reductions in hot flash frequency and severity compared to placebo during the six-week period. Men taking placebo had an average reduction of 2.15 hot flashes per day and a decrease of 4.85 points in daily severity scores. Those on 2.5 mg oxybutynin twice daily saw reductions of 4.77 hot flashes per day and a drop of 9.94 points in severity scores, while those on the higher dose experienced decreases of 6.89 hot flashes per day and a reduction of 13.95 points in severity.
Improvements often appeared within the first week and continued throughout the study period. A larger proportion of patients achieved at least a 50 percent reduction in hot flash scores with oxybutynin: 57 percent in the lower-dose group and 79 percent in the higher-dose group, compared with only 32 percent among those receiving placebo. The most common side effect reported was dry mouth.
"These results are incredibly encouraging," said Dr. Stish. "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."
Researchers from multiple institutions participated in this study, including Mayo Clinic locations in Rochester, MN; Scottsdale, AZ; Jacksonville, FL; as well as Alliance Protocol Operations in Chicago; Aspirus Regional Cancer Center (WI); Ellis Fischel Cancer Center (MO); Georgetown-Lombardi Comprehensive Cancer Center (DC); Gibbs Cancer Center (SC); Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine (NY); SCOR-Messino Cancer Centers (NC); Sidney Kimmel Cancer Center (MD); The Ohio State University (OH); and Yale University School of Medicine (CT).
The research received funding support from several grants awarded by the National Cancer Institute at the National Institutes of Health.
