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.