Daily use of sildenafil citrate, administered during and after radiotherapy, resulted in improved sexual function for patients with prostate cancer compared with placebo, according to study results presented at the 2012 American Society for Radiation Oncology Annual Meeting in Boston.
Sildenafil citrate (Viagra, Pfizer) is a phosphodiesterase type 5 inhibitor and considered a rehabilitation treatment for men after prostatectomy, according to background information in the study.
The study is considered the first prospective, randomized, double blind, placebo-controlled trial to determine whether daily, adjuvant use of sildenafil citrate during and after radiation therapy maintains erectile function in patients with prostate cancer.
For the study, researchers enrolled 290 patients with clinically localized prostate cancer who were treated with external beam radiation therapy and/or permanent interstitial implantation. Michael J. Zelefsky, MD, co-leader of the genitourinary disease management team at Memorial Sloan-Kettering Cancer Center, and colleagues assigned patients to two groups (2:1 randomization) — those who received a 50-mg dose daily of sildenafil citrate and those who received a placebo.
Patients received medication 3 days before their radiation treatment and continued with a daily dose for 6 months. Daily doses of sildenafil citrate or the placebo then were discontinued and taken on an as-needed basis.
Patients’ international index of erectile function (IIEF) scores were based on patient feedback regarding their erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall satisfaction, Zelefsky said.
Patients completed the IIEF and international prostate symptom score (IPSS) questionnaires before therapy and at 6, 12 and 24 months after radiation treatment.
Of the 290 patients enrolled, 144 completed the questionnaire before therapy and after at least one additional post-treatment time point.
Results from IIEF scores indicated that those in the sildenafil citrate group experienced significantly improved overall sexual function compared with the placebo group at 6 months (58.6 vs. 49.4; P=.006), 12 months (56.3 vs. 48.2; P=.02) and 24 months (54.9 vs. 47.6; P=.04).
Differences between the two groups became less apparent after 12 months, study results showed. Researchers found similar scores in both treatment groups for patient characteristics, including age, use of brachytherapy, androgen deprivation therapy and baseline IIEF scores.
“We conclude that patients who received [sildenafil citrate] demonstrated significant improvements in sexual function in a number of important domains, particularly overall satisfaction and the IIEF overall scores,” Zelefsky said. “We believe this study is important because it is the first randomized controlled trial demonstrating a benefit or pharmacologic intervention in a preventive mode, known as penile rehabilitation, in the treatment of patients who received radiotherapy for their prostate cancer.”
For more information:
Zelefsky MJ. Abstract #4. Presented at: 2012 ASTRO Annual Meeting; Oct. 28-31, 2012; Boston.
Disclosure: Zelefsky received a restricted-educational grant from Pfizer. Additional researchers received a restricted-educational grant from Pfizer for a different study.