Erectile function after permanent prostate brachytherapy

PURPOSE: To determine the incidence of potency preservation after permanent prostate brachytherapy using a validated patient-administered questionnaire and to evaluate the effect of multiple clinical and treatment parameters on penile erectile function. MATERIALS AND METHODS: Four hundred twenty-five patients underwent permanent prostate brachytherapy from April 1995 to October 1999. Two hundred nine patients who were potent before brachytherapy and who at the time of the survey were not receiving hormonal therapy were mailed the specific erectile questions of the International Index of Erectile Function (IIEF) questionnaire with a self-addressed stamped envelope. The questionnaire consisted of 5 questions, with a maximal score of 25. Of the 209 patients, 181 (87%) completed and returned the questionnaire. The mean and median follow-up was 40.4 +/- 14.9 and 40.6 months, respectively (range 19-75). Preimplant erectile function was assigned using a three-tiered scoring system (2 = erections always or nearly always sufficient for vaginal penetration; 1 = erections sufficient for vaginal penetration but considered suboptimal; 0 = the inability to obtain erections and/or erections inadequate for vaginal penetration). Postimplant potency was defined as an IIEF score >/=11. The clinical parameters evaluated for erectile function included patient age, preimplant potency, clinical T-stage, pretreatment prostate-specific antigen level, Gleason score, elapsed time after implantation, hypertension, diabetes mellitus, and tobacco consumption. Treatment parameters included radiation dose to the prostate gland, use of hormonal manipulation, use of supplemental external beam radiotherapy (EBRT), choice of isotope, prostate volume, and planning volume. The efficacy of sildenafil citrate in brachytherapy-induced erectile dysfunction (ED) was also evaluated. RESULTS: Pretreatment erectile function scores of 2 and 1 were assigned to 125 and 56 patients, respectively. With a 6-year follow-up, 39% of patients maintained potency after prostate brachytherapy, with a plateau on the potency preservation curve. Postimplant preservation of potency (IIEF >/=11) correlated with preimplant erectile function (50.4% vs. 13.2% for preimplant scores of 2 and 1, respectively, p <0.001), patient age (57.4%, 38.2%, and 21.9% for patients <60, 60-69, and >/=70 years old, respectively, p <0.004), use of supplemental EBRT (52.0% vs. 26.4% for patients without and with EBRT, p <0.001), and a history of diabetes mellitus (41.4% vs. 0% for patients without and with diabetes, respectively, p = 0.017). In multivariate analysis, clinical stage, radiation dose to the prostate gland, hormonal manipulation, choice of isotope, history of hypertension, and tobacco consumption had no effect on the ultimate preservation of potency. Only the preimplant potency score, use of supplemental EBRT, and diabetes maintained statistical significance. Sixty-two patients used sildenafil, with 53 (85%) reporting a favorable response. When potent patients were grouped with the ED patients who used sildenafil, the 6-year actuarial rate of potency preservation was 92%. Including the 70 impotent patients who never used sildenafil, the actuarial 6-year rate of potency preservation with and without pharmacologic support was 54% and 39%, respectively. CONCLUSION: Our results suggest that brachytherapy-induced ED is more common than previously reported and may be the result of obtaining patient information by means of a validated quality-of-life instrument by mail and not by personal interview. In multivariate analysis, only pretreatment potency, supplemental EBRT, and diabetes maintained statistical significance. Most patients with brachytherapy-induced ED responded favorably to sildenafil. Although the 6-year actuarial incidence of potency preservation was 39%, 52% of patients not receiving supplemental EBRT maintained potency. In addition, with pharmacologic support, 92% of patients maintained potency.