Daily tadalafil failed to preserve erectile function among men undergoing radiotherapy for prostate cancer, according to investigators. The report was published online April 1 in JAMA.
In what they described as the first study to assess tadalafil for prevention of erectile dysfunction, researchers proposed that in contrast to episodic, on-demand use of the drug, the regular, daily use might maintain erectile function during and after radiotherapy. They tested this treatment against placebo in a randomized double-blind clinical trial (NCT00931528) involving 242 men with stage II prostate adenocarcinoma and intact erectile function. The men were enrolled at 76 community-based and tertiary medical centers in the United States and Canada.
They took 5 mg tadalafil or a matching placebo for 24 weeks, beginning at the start of either external radiotherapy (63%) or brachytherapy (37%), and were followed at intervals for 1-4 years. The primary outcome – retained erectile function 6 weeks after completion of the study agent – was reported by 79% of men who took tadalafil and 74% of those who took placebo. This was not a significant difference, said Dr. Thomas M. Pisansky of the Mayo Clinic, Rochester, Minn., and his associates.
Tadalafil also was no better than placebo at preserving erectile function at the 1-year follow-up (72% vs 71%, respectively). It was no more effective than was placebo for any subgroup of patients, regardless of patient age (younger vs. older than 65 years) or type of radiotherapy. The active drug also failed to outperform placebo on a wide variety of secondary outcomes, including orgasmic function, sexual desire, intercourse satisfaction, fatigue, sexual well-being, marital adjustment, or partners’ sexual satisfaction (JAMA 2014 April 1 [doi:10.1001/jama.2014.2626]).
This study was conducted by the Radiation Therapy Oncology Group, which is supported by the National Cancer Institute, and by Eli Lilly, maker of tadalafil. Dr. Pisansky reported no disclosures.