Tadalafil (Cialis) and Erectile Dysfunction After Radiotherapy for Prostate Cancer: An Open-Label Extension of a Blinded Trial
Objectives: To determine the efficacy of tadalafil (Cialis) in patients with erectile dysfunction after three-dimensional conformal external beam radiotherapy for prostate cancer in an extended open-label phase of the blinded trial. Methods: Sixty patients entered a double-blind, placebo-controlled, cross-over study lasting 12 weeks. They received tadalafil 20 mg or placebo for 6 weeks and then crossed over to the alternate medication. Of these 60 patients, 51 (85%) entered a 6-week open-label extension phase. The data were collected using the International Index of Erectile Function (IIEF) questionnaire. Side effects were also recorded. Results: All patients completed the double-blind cross-over study. The 9 patients who did not wish to enter the open-label phase had had significantly worse scores statistically on the erectile function domain of the IIEF with tadalafil in the blinded trial (P = 0.03). For all IIEF domains, except for sexual desire, tadalafil was equally effective in the double-blind phase as in the open-label phase. For nearly all the IIEF questions, tadalafil caused a significant increase in the mean scores from baseline in the run-in period of the blinded trial. The side effects were mild or moderate and had significantly decreased compared with tadalafil in the blinded trial. Conclusions: Tadalafil is effective in many patients with erectile dysfunction after three-dimensional conformal external beam radiotherapy for prostate cancer. In the open-label extension of the trial, tadalafil showed the same efficacy as in the blinded phase.