Erectile dysfunction after radiotherapy for prostate cancer and radiation dose to the penile structures: a critical review.

Erectile dysfunction (ED) is a common sequela after external beam radiotherapy and brachytherapy for prostate cancer. There are several structures in the vicinity of the prostate that are critical to erectile function and that receive a substantial radiation dose: neurovascular bundles (NVBs), internal pudendal arteries (IPAs), accessory pudendal arteries, corpora cavernosa and the penile bulb. Most reports analyzing the correlation between radiation dose to these structures and radiation-induced ED are limited by the small number of patients analyzed in each study. So far, there is no evidence for a role of the NVBs in radiation-induced ED. There are no reports on the IPAs, based on reduced arterial flow in the penis. Several studies show contradicting results on the corpora cavernosa, which house the erectile tissue required for erection. There are contradicting reports on the penile bulb, although studies with more patients tend not to find any correlation. Sparing of the penile bulb to improve potency-preservation is not sufficiently supported by the current literature. If sparing of the penile bulb is achieved by reducing the margin for the apex, an oncological risk is taken, while it is uncertain whether this will improve potency-preservation.