According to a new study conducted by researchers from Cedars-Sinai in Los Angeles and published in the Journal of Urology, it has been revealed that the use of erectile dysfunction drugs, or phosphodiesterase type 5 (PDE-5is) inhibitors such as sildenafil may not reduce the risk of developing prostate cancer.
Erectile Dysfunction (ED) affects about 5% of 40-year-old men and between 15% and 25% of 65-year-olds. Drugs such as Viagra (sildenafil), Cialis (tadalafil), and Levitra (vardenafil) are phosphodiesterase type 5 inhibitors (PDE-5is) that are commonly used to treat ED. ED drugs were first introduced to the market in 1998, and have been found to be safe and effective. Past studies had even indicated that they may even protect men from developing prostate cancer.
“In vitro mouse studies have suggested that these drugs might have some anticancer activity, but the evidence in human subjects is mixed. Given the routine use of PDE-5 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.” –Lead investigator Stephen J. Freedland, MD
For the study, Freedland and colleagues followed 6,501 men for a period of four years. Of these men, 364 were using PDE-5is drugs. Over the course of the study, 19.5% of the men prescribed with erectile dysfunction drugs were diagnosed with prostate cancer. The rate was 22.7% in men who were not prescribed the drugs, a difference that the researchers considered as statistically insignificant. Additionally, researchers also looked at men in North America, where use of the erectile dysfunction drugs is more prevalent. The treatment was associated with an inverse trend of prostate cancer that approached but did not reach a statistical significance.
“PDE-5i use was not associated with decreased prostate cancer diagnoses on post-hoc analysis of REDUCE. In North American men, who had much higher baseline use of PDE-5i, this treatment was associated with an inverse trend of prostate cancer diagnosis that approached but did not reach statistical significance.”
Despite the size of their study, researchers expressed the need for additional studies in order to prove whether a link exists between ED drugs and a prostate cancer diagnosis, regardless of how small the evidence has been thus far. “Future studies with longer followup and larger study populations are warranted to determine the association between PDE-5i and prostate cancer,” said Dr. Juzar Jamnagerwalla, a urology resident at Cedars-Sinai.