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Tadalafil did not prevent erectile dysfunction after prostate radiotherapy
Daily use of tadalafil, a phosphodiesterase-5 inhibitor used to treat erectile dysfunction, did not result in improved erectile dysfunction for men who underwent radiotherapy for prostate cancer, study results showed.
The FDA has approved daily treatment with tadalafil (Cialis, Eli Lilly) in 2.5-mg or 5-mg doses for the prevention erectile dysfunction after the start of radiotherapy, but researchers found that 5 mg daily demonstrated no improvement in erectile dysfunction in men aged 18 years and older.
Thomas M. Pisansky, MD, of Mayo Clinic, and colleagues conducted the placebo-controlled, double blind, parallel-group study at 76 community-based and tertiary medical sites in the United States and Canada.
The analysis included 242 men with intact erectile function who were scheduled to receive radiotherapy for clinical stage 2 prostate adenocarcinoma. Researchers randomly assigned half of the patients to 5 mg tadalafil daily for 24 weeks, and the other half of patients received placebo.
The primary endpoint was to determine whether tadalafil maintained spontaneous erections between 28 and 30 weeks after the start of radiotherapy, which was 4 to 6 weeks after tadalafil treatment stopped.
At 6 weeks post-tadalafil treatment, the rate of erectile function retention was 79% (95% CI, 70%-88%) among those assigned the study drug and 74% (95%CI, 63%-85%) among those assigned placebo (P=.49), a difference that was not statistically significant. Researchers had predicted a 20% between-group difference.
At 1 year, the rate of erectile function retention was 72% (95% CI, 60%-84%) among those assigned tadalafil and 71% (95% CI, 59%-84%) among those assigned placebo (P=.93).
Researchers observed mild and/or moderate adverse effects in 59% of participants assigned tadalafil and 52% of participants assigned placebo. Severe or life-threatening adverse events were reported in 3% of patients assigned tadalafil and 1% of those assigned placebo.
“Based on evidence available presently, there is no support for phosphodiesterase-5 inhibitor use to prevent erectile dysfunction after highly conformal external radiotherapy or low-dose-rate brachytherapy,” Pisansky and colleagues wrote. “Alternative strategies to prevent erectile dysfunction in this context appear warranted, perhaps with attention toward alternative dosing, investigation of neuroprotective interventions or further refinements of radiotherapy delivery methods.”
Disclosure: The study was supported by Eli Lilly and NCI. The researchers report financial relationships with Augmenix, Bristol-Myers Squibb, Eli Lilly and other entities.
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