TOPLINE:

Among men with prostate cancer receiving androgen deprivation therapy (ADT), oxybutynin led to significant reductions in hot flash frequency, with the 5-mg twice-daily dose decreasing hot flashes by nearly seven per day compared with about two per day in the placebo group.

METHODOLOGY:

• Hot flashes are a common problem among men receiving ADT to treat prostate cancer and may affect whether men complete their recommended ADT regimen. Oxybutynin, commonly used to treat overactive bladder symptoms, has shown activity for managing hot flashes and could be helpful for men on ADT.
• In a randomized, double-blind, placebo-controlled phase 2 clinical trial, researchers assessed whether oxybutynin reduced hot flashes in patients (aged 18 years or older) who were receiving ADT for prostate cancer and reporting at least 28 hot flashes per week.
• Overall, 81 eligible patients were randomly assigned to receive oral oxybutynin 2.5 mg twice daily (n = 28), oxybutynin at 5 mg twice daily (n = 28), or placebo (n = 25) for 6 weeks.
• At baseline, patients had an average of 10.1 hot flashes per day (10.3 in both oxybutynin groups and 9.9 in the placebo group) and an average daily hot flash score of 18.2.
• The primary endpoint was the change in patient-reported hot flash scores since baseline at 6 weeks. Other outcomes included incidence of adverse events and changes in Hot Flash Related Daily Interference Scale scores.

TAKEAWAY:

• Patients receiving oxybutynin experienced a greater reduction in hot flash frequency: Patients receiving the 5-mg dose experienced the greatest average reduction of 6.89 hot flashes per day (P < .001) compared with 4.77 (P = .02) in the 2.5-mg dose group and 2.15 in the placebo group.
• Daily hot flash scores decreased significantly in the oxybutynin groups by an average of 13.95 points in the 5-mg group, 9.94 points in the 2.5-mg group, and 4.85 points in the placebo group.
• Hot Flash Related Daily Interference Scale total scores improved significantly in the oxybutynin groups as well: decreasing by 20.7 points (P < .01) with the 5-mg dose, 14.2 points (P = .042) with the 2.5-mg dose, and 3.1 points with placebo. Additionally, given that the placebo group also benefited in all three categories, the placebo effect may have been at work here as well, outside experts noted.
• Looking at tolerability, no grade 3 or higher adverse events were deemed related to oxybutynin. The researchers did consider some grade 2 adverse events “possibly, probably, or definitely” related to oxybutynin: none in the placebo arm, eight in the 2.5-mg group, and six in the 5-mg oxybutynin arm, with dry mouth being the most common.

IN PRACTICE:

Compared with placebo, “oxybutynin demonstrated a sustained, significant decrease in hot flash frequency, without serious treatment-related side effects,” the authors of the study concluded. These data “provides strong support for its use to manage hot flash symptoms in men receiving ADT.”

SOURCE:

The study, led by Bradley Stish, MD, Mayo Clinic Department of Radiation Oncology, Rochester, Minnesota, was published online in the Journal of Clinical Oncology.

LIMITATIONS:

While this phase 2 trial provided encouraging evidence for oxybutynin use in managing hot flashes in men with prostate cancer on ADT, the study was small. Larger trials are needed to confirm the findings in a larger, more diverse population and to determine optimal dosing of oxybutynin.

DISCLOSURES:

The study was supported by the National Cancer Institute of the National Institutes of Health. Several authors reported having disclosures, including Scott Tagawa, MD, who disclosed receiving consulting fees from multiple pharmaceutical companies including Medivation, Astellas Pharma, and Janssen, as well as Charles Loprinzi, MD, who reported consulting relationships with several pharmaceutical companies including Metys Pharmaceuticals, Disarm Therapeutics, and OnQuality Pharmaceuticals.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.