66: A Randomized, Double-Blind, Placebo-Controlled, Cross-Over Study to Assess the Efficacy of Tadalafil (Cialis®) in the Treatment of Erectile Dysfunction Following Three-Dimensional Conformal External-Beam Radiotherapy for Prostatic Carcinoma

Abstract

Prostatic carcinoma has become the most frequent non-skin male malignancy in Western countries. Erectile dysfunction after three-dimensional conformal external-beam radiotherapy (3DCRT) for prostatic carcinoma is reported in up to 64% of the patients carcinoma. The purpose of this study was to determine the efficacy of the oral drug tadalafil (Cialis®) in patients with erectile dysfunction after radiotherapy for prostatic carcinoma. 358 patients who completed radiotherapy at least 12 months prior to the study were approached by mail. All patients had been treated by 3DCRT. Sixty patients were included and entered a double-blind, placebo-controlled, cross-over study lasting 12 weeks. They received 20 mg of tadalafil or placebo for 6 weeks. At 6 weeks patients crossed over to the alternative treatment. Drug or placebo was taken on demand at patient’s discretion, with no restrictions regarding the consumption of alcohol or food, at least once a week and no more than once daily. Data were collected using the Sexual Encounter Profile (SEP) and the International Index of Erectile Function (IIEF) questionnaires. Side-effects were also recorded, using a patient-completed standardized form, after each treatment period. Comparison between tadalafil scores and placebo scores was done using Wilcoxon’s matched pairs test. For within- and between-group comparison of percentages, McNemar’s test and Fisher’s exact test were used, respectively. Mean age at study entry was 69 years. All patients completed the study. For almost all questions of the IIEF questionnaire there was a significant increase in mean scores from baseline with tadalafil, but not with placebo. For all the IIEF domains there was a statistically significant difference between tadalafil and placebo. Sixty-seven percent of the patients reported an improvement of erectile function with tadalafil (placebo: 20%) and 48% reported successful intercourse with tadalafil (placebo: 9%) (p<0.0001). Side effects were mild or moderate. Except for headache, flushing and dyspepsia, all other reported adverse events did not differ significantly between the two treatments (tadalafil or placebo). No patient decreased the dose to 10 mg. Tadalafil is an effective treatment for erectile dysfunction after 3DCRT for prostatic carcinoma with successful intercourse reported in almost 50% of the patients, and is well tolerated.