Long-term potency after iodine-125 radiotherapy for prostate cancer and role of sildenafil citrate.

Objectives: To assess the long-term sexual potency and attrition in sexual function after iodine-125 ((125)I) seed radiotherapy and the effect of sildenafil on radiation-induced erectile dysfunction (ED).

Methods: This prospective study consisted of 86 sexually active patients (mean age 63.5 +/- 7.7 years) who underwent (125)I seed implantation from 1997 to 1999 to treat low-volume prostate cancer (prostate-specific antigen less than 10 ng/mL, Gleason score 6 or less, stage T1-T2). All patients were followed up every 6 to 8 months for 4 years. Patients prescribed sildenafil citrate for ED completed the abridged five-item version of the International Index of Erectile Function (IIEF) and the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaires.

Results: The median follow-up was 49.7 months (range 36 to 66). Of 86 patients, 43 (50%) did not initiate drug therapy; and only 36 (83.7%) of the 43 were interviewed at 4 years. Twenty-three (63.8%) of the 36 patients had erections sufficient for vaginal penetration, with a total mean +/- SD IIEF-5 score of 15.76 +/- 1.13. The other 50% (43 of 86) initiated sildenafil citrate for treatment of ED after seed implantation, with a minimal follow-up of 6 months. At 4 years, 32 (74%) of the 43 were responding positively to sildenafil citrate, with a total IIEF-5 score of 18.3 +/- 1.2. The mean EDITS +/- SD score was 76.5 +/- 3.2, and the spousal satisfaction rate was 72% (31 of 43). The dropout rate was 37% (16 of 43); 10 (63%) of the 16 discontinued because of a lack of efficacy, 3 (19%) because of a return of natural erections sufficient for vaginal penetration, and 3 (19%) discontinued because of side effects (headaches).

Conclusions: ED is a major long-term issue after (125)I seed radiotherapy, with a long-term potency rate of 29%. Sildenafil citrate improves erections in most patients after (125)I seed implantation.