Dose of radiation received by the bulb of the penis correlates with risk of impotence after three-dimensional conformal radiotherapy for prostate cancer

Objectives. To evaluate the effect of the dose to the bulb of the penis on postradiation potency. Methods. Twenty-one patients reporting potency before three-dimensional con formal radiotherapy had the dose delivered to the bulb of the penis evaluat ed. This was then compared with the patient assessments of post-treatment s exual function to determine whether a dose-volume relationship exists. Results. Among the patients analyzed to date, a strong dose-volume relation ship and the likelihood of remaining potent after treatment seems to exist. Patients receiving a dose of less than 40 Gy to 70% of the bulb of the pen is appear to have a much greater likelihood of maintaining potency. Patient s receiving 70 Gy or more to 70% of the bulb of the penis appear to be at v ery high risk of experiencing radiation-induced impotence (P = 0.03). Conclusions. More studies are needed to confirm these observations. If conf irmed, these data suggest that by using three-dimensional-based treatment p lanning and carefully designed treatment fields, the potency of men treated with radiotherapy might be substantially improved. UROLOGY 57: 955-959, 20 01. (C) 2001, Elsevier Science Inc.