John J. Mulcahy, MD, PhD

John J. Mulcahy, MD, PhD, a member of the Urology Times editorial council, is professor of urology, Indiana University Medical Center, Indianapolis.

Prostate cancer treatments can have deleterious effects on a patient's erections, as the nerves and vasculature associated with the erectile process are in proximity to the prostate. Nerve-sparing prostatectomy and more targeted irradiation techniques have helped minimize damage to surrounding tissues. 

In spite of these advances, the incidence of ED after prostate cancer treatment remains significant. If a medication used to treat ED, such as intracorporeal papaverine, phentolamine mesylate, prostaglandin E-1 (alprostadil [Caverject]), or trimix (papaverine, phentolamine, and prostaglandin E-1), is effective after treatment, it is invariably at higher doses, suggesting a vascular, rather than a neural problem. An accessory pudendal artery has been suggested, the vascular bed of which may have been compromised during prostate removal or irradiation. 

When the prostate is removed surgically, the effect on erections is immediate. As the effect of irradiation is the acceleration of endothelial hyperplasia, vascular insufficiency may be more gradual, with ED occurring in about 20% of patients within the first year, but in 80% within 5 years. 

A study commissioned by Pfizer a number of years ago compared a group of patients given daily sildenafil citrate (Viagra) following bilateral nerve-sparing prostatectomy with a group given daily placebo. All patients were fully potent preoperatively, as determined by questionnaire and nocturnal Rigiscan testing. More than one-fourth (27%) of the sildenafil group showed a return of potency at 8 months, whereas usable erections returned in 4% of the placebo group. 

Because the estimates regarding the incidence of ED following the treatment of prostate cancer are variable and possibly inaccurate, how are we to counsel patients when discussing therapeutic options? I believe patients should be advised that ED is a good possibility with any form of treatment, but that any degree of ED can be successfully treated in the motivated patient. 

The use of PDE-5 inhibitors frequently, if not daily, has been shown to enhance volitional as well as nocturnal erections, and offers a greater likelihood of eventual return of spontaneous erections. Lifestyle modifications to reduce vascular disease (maintaining ideal body weight, aerobic exercise, and stopping smoking) help to optimize the vascular environment as much as possible under the circumstance. A partner who supports the patient emotionally and sexually in this period of penile rehabilitation is helpful, as well. 

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