Potency preservation after three-dimensional conformal radiotherapy for prostate cancer - Preliminary results

We sought to assess potency preservation after three-dimensional conformal radiotherapy (3D-CRT) in prostate cancer patients eligible for radical pros tatectomy, conventional radiotherapy, 3D-CRT, or transperineal prostate imp lantation. Patients with more advanced disease are commonly treated with ho rmonal therapy, which can cause impotence, and were consequently excluded f rom the analysis. Between December 1991 and June 1998, 198 prostate cancer patients were treated with 3D-CRT at the University of California, Davis Me dical Center. Fifty-two of these patients had a pretreatment prostate-speci fic antigen (PSA) level of 10.0 ng/ml or less, a Gleason score of 6 or less , and a 1997 AJCC clinical stage T1bN0M0 to T2bN0M0. One patient was not ev aluable. None of the 51 evaluable patients had diabetes mellitus. In 40 pat ients, the prostate gland only was irradiated to a total dose of 66 to 79.2 Gy by using daily 1.8-Gy fractions. In 11 patients, the prostate and semin al vesicles were treated to 44 to 55.8 Gy. Lymph nodes were not included in the clinical target volume. The median age was 68 years, and the median le ngth of follow-up was 15 months. Potency in this study is defined as an ere ction sufficient for vaginal penetration. Kaplan-Meier analysis was used to describe potency as a function of time after 3D-CRT. Of the 51 evaluable p atients, 35 (69%) were potent, 15 were impotent, and 1 was sexually inactiv e before 3D-CRT. Kaplan-Meier estimates of the potency preservation rates 1 , 2, and 3 years after SD-CRT are 100%, 83%, and 63%, respectively. On mult ivariate analysis, age, total radiation dose, and a history of transurethra l resection of the prostate did not significantly affect potency preservati on rates. Three (43%) of 7 patients who became impotent after 3D-CRT and us ed sildenafil were subsequently able to achieve erections sufficient for va ginal penetration. The preliminary results reported herein suggest that app roximately two thirds of prostate cancer patients will retain their potency 3 years after 3D-CRT. Further follow-up is necessary to assess long-term p otency after 3D-CRT. Sildenafil should be considered in patients who develo p radiation-induced impotence.