Delaying onset of erectile dysfunction when receiving radiation therapy

Daily treatment with sildenafil citrate (Viagra) seems to have been able to help maintain erectile function for up to 2 years among men receiving such adjuvant treatment during and after radiotherapy for localized prostate cancer.

A paper by Zelefsky et al., just published on line in the Journal of Urology, describes the results of a randomized, prospective trial in 279 patients with localized prostate cancer, all treated with radiotherapy, in which treatment with adjuvant sidenafil (at 50 mg/day) was compared to adjuvant treatment with a placebo. Treatment with sildenafil or the placebo was started 3 days before radiation therapy and continued daily for 6 months. Two patients were randomized to receive sildenafil for each patient randomized to the placebo (2:1 randomization).

Patients completed validated survey tools regarding erectile and sexual function at 3, 6, 9, 12, 18, and 24 months post-radiotherapy.

Here are the key study findings:

  • 279 patients were enrolled in the trial and provided data for analysis.
  • At 12 months after completion of radiotherapy,
    • Erectile function scores were better for men on sildenafil than those on placebo (P = 0.018).
    • 73 percent of sildenafil patients had mild or no erectile dysfunction compared to 50 percent of placebo patients (P = 0.024).
    • Men in the sildenafil arm of the trial reported superior overall satisfaction scores (P = 0.028) and International Index of Erectile Function (IIEF) total scores (P = 0.044) than those on placebo.
  • At 24 months after completion of radiotherapy,
    • Erectile function scores were no longer significantly better for men on sildenafil compared to those on placebo (P = 0.172).
    • Men in the sildenafil arm of the trial reported better overall sexual satisfaction scores (P = 0.032) and marginally better IIEF scores (P = 0.097) that those on placebo.
    • Men in the sildenafil arm of the trial reported higher scores for sexual desire (P = 0.049) than those on placebo — even though they had completed drug therapy 18 months earlier.
    • 81.6 percent of  sildenafil patients had functional erections (with or without ED medication) compared to 56.0 percent of placebo patients (P = 0.045).

The authors conclude that daily treatment with sildenafil, during and after radiotherapy for prostate cancer, is associated with improved overall sexual function compared with placebo for various sexual function domains.

They also note that this trial is the first randomized, prospective, controlled trial to demonstrate utility of a phosphodiesterase-5 (PDE5) inhibitor as a rehabilitation strategy in prostate cancer radiation therapy patients.

The benefit of 6 months of treatment with sildenafil citrate in this set of patients does seem to be clinically significant. However, it is clear that this effect is wearing off within about 2 years post-treatment. Whether this decline in erectile/sexual function at 2 years is a consequence of radiation therapy, or aging, or both is, of course, harder to determine.

One Response

  1. Thanks for the chuckle. I enjoyed the pun in the last sentence of the article.

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