A study of penile circulation before and after radiation in patients with prostate cancer and its effect on impotence.

Decrease in penile blood flow has been implicated as the cause of erectile impotence in patients receiving pelvic irradiation. To determine any changes in the penile circulation secondary to pelvic irradiation, we measured the penile blood flow before and 6-9 months following completion of irradiation in six patients with prostate cancer. None of these patients had hormonal manipulation. The non-invasive techniques of Penile Brachial Index (PBI) and Penile Flow Index (PFI) were used to study penile circulation. Two patients developed impotence 2 to 4 1/2 months following completion of irradiation. There was no significant change in penile blood flow following irradiation in any of the six patients studied. The etiology of post-irradiation impotence is probably multifactorial and it may be an oversimplification to attribute it to a single organic cause.