Dose of radiation received by the bulb of the penis correlates with risk of impotence after three-dimensional conformal radiotherapy for prostate cancer.
OBJECTIVE
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 conformal radiotherapy had the dose delivered to the bulb of the penis evaluated. This was then compared with the patient assessments of post-treatment sexual function to determine whether a dose-volume relationship exists.


RESULTS
Among the patients analyzed to date, a strong dose-volume relationship 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 penis appear to have a much greater likelihood of maintaining potency. Patients receiving 70 Gy or more to 70% of the bulb of the penis appear to be at very high risk of experiencing radiation-induced impotence (P = 0.03).


CONCLUSIONS
More studies are needed to confirm these observations. If confirmed, these data suggest that by using three-dimensional-based treatment planning and carefully designed treatment fields, the potency of men treated with radiotherapy might be substantially improved.
Fisch
B M
BM
Department of Radiation Oncology, University of California, San Francisco, School of Medicine, San Francisco, California, USA.
Pickett
B
B
Weinberg
V
V
Roach
M
M
D000368:Aged; D004307:Dose-Response Relationship, Radiation; D007172:Erectile Dysfunction / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D007989:Libido / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D010413:Penis / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods; D012307:Risk Factors; D012725:Sexual Behavior / Q000528:radiation effects