Phosphodiesterase type 5 (PDE5) inhibitors, which are prescribed to treat erectile dysfunction (ED), do not appear to reduce the risk of developing prostate cancer, according to new research published in the Journal of Urology.
This class of drugs includes sildenafil, tadalafil, and vardenafil. Studies in mice have shown the potential for preventing cancer with PDE5 inhibitors, but similar research on humans has had mixed results.
For this study, a group of researchers from the United States examined data from another study called REDUCE, which lasted for four years. The REDUCE study focused on the enlarged prostate drug dutasteride and prostate cancer risk. All of the participants of the REDUCE study had biopsies at two- and four-year points, which helped the researchers assess their cancer status.
“Given the routine use of [PDE5 inhibitors] and the possibility that these agents may have anticancer activity, we wanted to test the association between their use and risk of developing prostate cancer,” said lead investigator Stephen J. Freedland, MD of the Samuel Oschin Comprehensive Cancer Institute at Cedars-Sinai Medical Center in Los Angeles in a press release.
To learn more about PDE5 inhibitors and prostate cancer risk, the scientists looked at information from 6,501 men who were involved with the REDUCE Trial. Overall, about 6% of them used a PDE5 inhibitor at the start of the study. Roughly 20% of the men who took the ED drugs were eventually diagnosed with prostate cancer, compared to 23% of the men who did not take PDE5 inhibitors.
Using a PDE5 inhibitor seemed to have no effect on the rate or severity of the cancer.
The researchers also considered a subset of North American men, as this geographic area tends to have higher rates of PDE5 inhibitor use than other parts of the world. While they found a small correlation between the use of ED drugs and fewer prostate cancer diagnoses, the results were not statistically significant.
The study did have some limitations. The scientists did not know how often men took PDE5 inhibitors, nor did they know the doses. They also didn’t know whether men started or stopped using these drugs during the study period.
Future research with larger groups of men and longer follow-up periods would help scientists learn more about any connection between ED drugs and prostate cancer, the authors noted.
“No Link Found between Erectile Dysfunction Drugs and Risk of Prostate Cancer”
(Press release. August 1, 2016)
The Journal of Urology
Jamnagerwalla, Juzar, et al.
“The Association between Phosphodiesterase Type 5 Inhibitors and Prostate Cancer: Results from the REDUCE Study”
(Full-text. Published online: April 5, 2016)