Cancer Health Center

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With the advent of sildenafil (Viagra), a phosphodiesterase-5 (PDE-5) inhibitor used to treat erection problems,[9] the percentage of men who seek treatment for erection problems has increased. Despite the publicity about the effectiveness of sildenafil, the drug works best in men with the mildest forms of erectile dysfunction. Many men will be unable to achieve adequate erections by taking this drug alone. The use of sildenafil enables about 72% of men with nerve-sparing prostatectomy and 15% of men with non-nerve-sparing prostatectomy to achieve erections sufficient for vaginal intercourse. Radical prostatectomy can result in nerve injury, in addition to vascular and smooth muscle damage. Injury and prolonged flaccidity of the penis can result in hypo-oxygenation of the penile tissue, further complicating structural integrity and compromising future erectile function.[10] The process of healing after surgery takes approximately 3 to 6 months, and full recovery can be expected at 1 year postsurgery. However, during this time, it is important for men to continue to have erections to keep the tissue healthy with adequate blood flow and to improve their future ability to have adequate erections. Therefore, early penile rehabilitation is recommended.[11]

In one nonrandomized study, 84 men who had undergone nerve-sparing radical prostatectomy could choose whether to start early rehabilitation or to wait.[12] In this study, early rehabilitation was defined as beginning activities to achieve erections within 6 months of radical prostatectomy, while delayed rehabilitation was defined as starting such activities more than 6 months after radical prostatectomy. Rehabilitation consisted of the use of sildenafil citrate, 100 mg, on four occasions. If erection sufficient for vaginal penetration was not achieved, then men were encouraged to use penile injections to obtain erections. Those who responded well to sildenafil citrate continued using this agent. Forty-eight men chose early rehabilitation, and 36 men chose delayed rehabilitation. The men were matched for age, comorbidities, and baseline erectile function, with a mean age of 58 years. Outcomes were evaluated with the International Index of Erectile Function (IIEF) and were assessed presurgery and at 1 and 2 years postsurgery. Trends for better scores on the IIEF were seen at 1 year, but statistically significant differences were not realized until year 2, with significantly more men in the early rehabilitation arm having unassisted functional erections (48% vs. 33%) and more men in the early group having functional erections with sildenafil (76% vs. 45%). Twenty-four percent of men in the early rehabilitation group had normal erectile function scores as measured by the IIEF, compared to 8% of men in the delayed rehabilitation group.[12][Level of evidence: II] Some data suggest that about 12% of sildenafil responders lose efficacy by 3 years.[13][Level of evidence: III]

In a study of brachytherapy in the treatment of localized prostate cancer, sildenafil improved potency in 62% to 70% of patients.[14] Patients who were not being treated with androgen therapy had a significantly better response.[15] Similarly, of men who became impotent after brachytherapy for prostate cancer,[16] 85% to 88% responded with improved erectile function when taking sildenafil. Reported potency rates after prostate brachytherapy are high; a 3-year follow-up study demonstrated that 80% of patients were able to have erections adequate for satisfactory sexual activity with or without sildenafil.[17][Level of evidence: II] Sildenafil has also improved erectile function for patients with partial parasympathetic nerve disruption from rectal surgery.[18][Level of evidence: I][19][Level of evidence: II] No other treatment for erectile dysfunction has a high rate of patient acceptance. Sildenafil has been studied in a novel primary prevention modality using nightly administration after a bilateral nerve-sparing prostatectomy. This approach effected a sevenfold improvement in return of spontaneous, normal erectile function 2 months after discontinuation of the drug.[20][Level of evidence: IV] The authors state that this effect appears to be mediated by properties unique to sildenafil that include improved endothelial function and neuronal regeneration and neuroprotection.[20]