Small study shows no long-term benefit in preventing loss of erectile function


Data from a newly-published (but very small) randomized, double-blind, placebo-controlled clinical trial show no significant, clinical impact of sildenafil (Viagra®) taken once daily as a treatment to optimize retention of erectile function at up to 2 years after radiation therapy for localized prostate cancer.

An Australian clinical research team (Ilic et al.) randomized just 27 men to either sildenafil or a placebo taken once daily for a period of 6 months. All patients had been treated with external beam radiation therapy for localized prostate cancer at a single center. The abstract of the paper does not state this specifically, but one has to assume that all 27 patients had at least reasonable erectile function prior to their radiation therapy.

The primary study end-point was erectile function, as measured by the International Index of Erectile Function (IIEF) score, at 2 years of follow-up. The abridged IIEF-5 survey was also used during the treatment period, and could be derived from the full IIEF at other time points.

Here are the basic study findings:

  • There was no evidence of any significant difference of the IIEF scores between the sildenafil and the placebo groups at 2 years of follow-up.
  • Patients randomized to the sildenafil group did have significantly better IIEF-5 scores at 4 weeks (P = 0.02) and at 6 months (P = 0.02) post-radiation (i.e., while they were on active drug therapy).
  • There was no evidence of any significant difference in adverse events between the two groups.

Having said that, the abstract gives us no information about the ages, the clinical stages, the PSA levels or the Gleason scores of the patients pre-treatment. Nor does it inform us about the type of radiation therapy utilized or the radiation dose administered, so exactly how much one can extrapolate from this study is  rather less than evident (especially since the number of patients is so small).

The authors conclude that, “There was no evidence from this trial that sildenafil provides long-term erectile function for patients while on medication.” They also state that,  “Regular use of sildenafil may improve short-term sexual function for patients while on medication.”

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