(ChemotherapyAdvisor) – Daily adjuvant use of sildenafil citrate during radiotherapy to treat patients with prostate cancer improved overall sexual function vs placebo at all time points, a study presented during the American Society for Radiation Oncology’s (ASTRO’s) 54th Annual Meeting, held in Boston, MA, has found.

In presenting results of the first randomized, prospective trial to demonstrate utility of a phosphodiesterase type 5 (PDE5) inhibitor as penile rehabilitation in patients with prostate cancer undergoing radiation therapy, Michael J. Zelefsky, MD, of Memorial Sloan-Kettering Cancer Center, New York, NY, said, “the most significant improvements were seen at 6 and 12 months following treatment, with a slight dip at the 24-month mark, suggesting that future trials need to be conducted to demonstrate if a longer treatment duration can further improve patient outcomes.”

A total of 290 patients with clinically localized prostate cancer treated with external beam radiation therapy and/or permanent interstitial implantation were randomly assigned to receive sildenafil citrate 50mg/day or placebo, which was initiated 3 days prior to treatment and continued daily for 6 months, “after which the drug therapy was discontinued and taken on an as-needed basis,” Dr. Zelefsky noted.

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Each patient completed the International Index of Erectile Function (IIEF)—which included the domains of erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction—and International Prostate Symptom Score (IPSS) questionnaires pretherapy and at 6, 12 and 24 months posttreatment.

Baseline characteristics were similar in each arm, including age, use of brachytherapy, androgen deprivation therapy, and baseline IIEF scores.

Among the 114 patients who completed the questionnaires before therapy and at least one time point and did not receive hormone therapy, those in the sildenafil citrate group had improved overall sexual function vs placebo: IIEF scores were 58.6 vs 49.4 at 6 months (P=0.006), 56.3 vs. 48.2 at 12 months (P=0.02), and 54.9 vs. 47.6 at 24 months (P=0.04), respectively.

Overall satisfaction was 8.0 in the sildenafil citrate arm at 6 months vs 6.5 for placebo (P=0.003); at 12 months, it was 7.4 vs 6.5 (P=0.05); and, at 24 months, it was 7.3 vs 6.4 (P=0.04).

Abstract (click on Paper Number 3)