Longitudinal comparison of sexual function after 3-dimensional conformal radiation therapy or prostate brachytherapy

Purpose: The risk of erectile dysfunction can influence treatment decisions for localized prostate cancer. To estimate the risk from 2 popular radiotherapies we compared erectile function and overall satisfaction with sexual function after 3-dimensional (D) conformal radiation therapy and transperineal prostate brachytherapy. Materials and Methods: A total of 128 patients with prostate cancer underwent 3-D conformal radiation therapy (median dose 70.2 Gy. to the planning target volume) and 60 underwent ¹⁰³palladium transperineal prostate brachytherapy (median dose 90 or 115 Gy. to 80% of the prostate with or without external nonconformal beam radiation therapy. Of the 128 patients 47 (37%) also received a luteinizing hormone releasing hormone (LH-RH) agonist (3 to 4 months), whereas 26 (43%) of the 60 patients received external beam radiation therapy and LH-RH (8 to 9 months). We evaluated erectile function and overall satisfaction with questions from validated, self-administered questionnaires. Patients responded to the questions serially before any prostate cancer therapy and at regular followup visits thereafter. We used the time until a patient returned to baseline erectile function and overall satisfaction to compare treatment modalities. Results: Median followup was 21 months. Of patients receiving 3-D conformal radiation therapy with or without LH-RH agonists 65% (95% CI 47% to 82%) and 67% (53% to 81%), respectively, returned to baseline overall satisfaction within 12 months after treatment versus 23% (9% to 50%) and 56% (38% to 75%) of the patients treated with transperineal prostate brachytherapy with or without external beam radiation therapy and LH-RH agonists, respectively. Reductions in overall satisfaction appeared to relate to changes in erectile function. Conclusions: These data suggest that in the absence of LH-RH agonist use 3-D conformal radiation therapy and transperineal prostate brachytherapy have a similar impact on erectile function and overall satisfaction. Differences observed in erectile function and overall satisfaction in the 2 groups of patients who received adjuvant LH-RH may be due to the different duration of therapy (3 versus 8 months). Longer followup will be needed to evaluate this hypothesis.