For men undergoing radiotherapy treatment for prostate cancer, a daily dose of sildenafil citrate (SC) might help improve sexual function, according to American researchers.
Such treatment could eventually be considered for penile rehabilitation protocols, they added.
Erectile dysfunction (ED) is common after prostate cancer treatment. Radiotherapy can damage vascular and endothelial tissue and, consequently, lead to ED. The researchers considered the vascular benefits of SC and questioned whether it could help men treated with radiotherapy.
They enrolled 279 men with localized prostate cancer who were about to begin radiotherapy treatment. About two-thirds of the men were over age 65. About 10% were also receiving androgen-deprivation therapy (ADT), which often affects sexual function.
Two hundred two men started the treatment program. They were randomly assigned to take either 50 mg of SC (125 men) or a placebo (77 men) daily for six months after the start of radiotherapy.
To assess sexual function, urinary symptoms, and quality-of-life issues, the researchers used questionnaires, including the International Prostate Symptom Score (IPSS) and the Rand 36-Item Health Survey (QOL). They also used the International Index of Erectile Function-6 (IIEF-6) to evaluate the following domains: erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction.
These assessments were taken at baseline and at three, six, nine, twelve, eighteen, and twenty-four months after radiotherapy began.
Comparing the two groups at the twelve-month mark, the researchers found that the men taking SC had better scores on the overall IIEF-6 as well as the erectile function and the overall satisfaction domains. Seventy-three percent of the men in the SC group had mild or no ED compared to 50% of the men in the placebo group.
After twenty-four months, the overall IIEF-6 and erectile function domain scores were not significantly better for the men taking SC, although they did have better scores on the overall satisfaction and sexual desire domains. At this point, about 82% of the SC group and 56% of the placebo group could achieve functional erections with or without ED drugs.
The men on androgen-deprivation therapy did not fare as well. Those taking SC or placebo had lower erectile function scores, suggesting that the sexual side effects of ADT were still strong, even when SC was included in treatment.
Men taking SC were more likely to have treatment side effects, which included dizziness, headaches, blurred vision, and flushing.
The authors noted that while the SC group was still seeing improvements at 24 months, the degree of improvement had leveled off when compared to those taking the placebo. They explained that the greatest improvements were seen at the six- and twelve-month assessment points, suggesting that the six-month treatment protocol may not be long enough. Further studies could explore whether longer treatment programs would have better results.
The study was published online as an accepted manuscript by The Journal of Urology.
The Journal of Urology
Zelefsky, Michael J., MD, et al.
“Prophylactic Sildenafil Citrate Improves Selected Aspects of Sexual Function in Men Treated by Radiotherapy for Prostate Cancer”
(Article in Press. Full-text accessed via ScienceDirect. Published online: March 3, 2014)