• Oren M Shemtov, Sidney B Radomski, and Juanita Crook.
• School of Medicine, Queen's University, Kingston, Ontario, Canada.
• Can J Urol. 2004 Dec 1; 11 (6): 2450-5.

PurposeWe undertook to determine if any significant differences in the efficacy of sildenafil citrate for erectile dysfunction (ED) exists between patients who have received external beam radiation or brachytherapy for prostate cancer.Materials And MethodsThirty-one patients who had received external beam radiation and nineteen patients who had received brachytherapy for prostate cancer and were subsequently treated with sildenafil citrate for post-irradiation ED comprised the patient population. A chart analysis was performed to determine either the presence or absence of concomitant risk factors for ED (coronary artery disease, diabetes, hypertension and smoking history) as well as age at radiation and time lapse between radiation completion and sildenafil citrate administration. Patients were then contacted to ascertain sildenafil citrate efficacy (defined as the continued use of sildenafil citrate), dosage used and medication tolerance.ResultsContinued use of sildenafil citrate was reported by 12/19 (63%) of the brachytherapy patients and 7/31 (22%) of the external beam radiation patients, a significant difference (P<0.007). Of those with continued use of sildenafil citrate, the patients who had undergone external beam radiation had a longer mean period of use (33.7 months) than those who had been treated with brachytherapy (14.3 months) (P=0.006). The mean elapsed time between completion of radiation and administration of sildenafil citrate was 7.6 months and 21.6 months for the brachytherapy and external beam radiation patients respectively (P=0.002). A significant difference in mean age existed between the patient groups, with the external beam radiation group being significantly older (69.8 years and 65.1 years respectively, P=0.007) at the time of sildenafil citrate administration. Of the risk factors for ED examined in each patient group, none were found to predict treatment failure with sildenafil citrate. Of the patients who did not experience success with sildenafil citrate, both groups used the medication for comparable periods of time.ConclusionsSildenafil citrate improved ED in a significantly greater number of patients who had undergone brachytherapy over those who had received external beam radiation. However, the patients who had received external beam radiation were both older and experienced a longer lapse of time between completion of radiotherapy and administration of sildenafil citrate than the brachytherapy patient group. This may explain the poorer success in the external beam radiation patients. The success of sildenafil in both groups of patients was lower than has previously been reported.

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