Sexual function after stereotactic body radiotherapy for prostate cancer: results of a prospective clinical trial.

PURPOSE: To study the sexual quality of life for prostate cancer patients after stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS: Using the Expanded Prostate Cancer Index Composite (EPIC)-validated quality-of-life questionnaire, the sexual function of 32 consecutive patients who received prostate SBRT in a prospective Phase II clinical trial were analyzed at baseline, and at median times of 4, 12, 20, and 50 months after treatment. SBRT consisted of 36.25 Gy in five fractions of 7.25 Gy using the Cyberknife. No androgen deprivation therapy was given. The use of erectile dysfunction (ED) medications was monitored. A comprehensive literature review for radiotherapy-alone modalities based on patient self-reported questionnaires served as historical comparison.

RESULTS

Median age at treatment was 67.5 years, and median follow-up was 35.5 months (minimum 12 months). The mean EPIC sexual domain summary score, sexual function score, and sexual bother score decreased by 45%, 49%, and 25% respectively at 50 months follow-up. These differences reached clinical relevance by 20 months after treatment. Baseline ED rate was 38% and increased to 71% after treatment (p = 0.024). Use of ED medications was 3% at baseline and progressed to 25%. For patients aged <70 years at follow-up, 60% maintained satisfactory erectile function after treatment compared with only 12% aged ≥70 years (p = 0.008). Penile bulb dose was not associated with ED.

CONCLUSIONS

The rates of ED after treatment appear comparable to those reported for other modalities of radiotherapy. Given the modest size of this study and the uncertainties in the physiology of radiotherapy-related ED, these results merit further investigations.