The Association between Phosphodiesterase Type 5 Inhibitors and Prostate Cancer: Results from the REDUCE Study

Purpose Despite routine use of phosphodiesterase type 5 inhibitor to treat erectile dysfunction the role in prostate cancer chemoprevention remains unclear. Only a few studies have explored the link between phosphodiesterase type 5 inhibitor use and prostate cancer. We tested the association between phosphodiesterase type 5 inhibitor and prostate cancer risk in the REDUCE (Reduction by Dutasteride of Prostate Cancer Events) trial. Materials and Methods REDUCE was a 4-year multicenter study testing the effect of daily dutasteride on prostate cancer risk in men with prostate specific antigen 2.5 to 10.0 ng/ml and negative biopsy who underwent study mandated biopsies at 2 and 4 years. The association of phosphodiesterase type 5 inhibitor with overall prostate cancer risk and disease grade (Gleason 2-6 and 7-10) was examined using adjusted logistic and multinomial regression analysis. Secondary analysis was performed to explore the association between phosphodiesterase type 5 inhibitor and prostate cancer risk in North American men, given the significantly higher use of phosphodiesterase type 5 inhibitor in these subjects. Results Phosphodiesterase type 5 inhibitor was not associated with prostate cancer diagnosis (OR 0.90, 95% CI 0.68–1.20, p = 0.476), low grade disease (OR 0.93, 95% CI 0.67–1.27, p = 0.632) or high grade disease (OR 0.85, 95% CI 0.51–1.39, p = 0.508). An inverse trend was seen between phosphodiesterase type 5 inhibitor and prostate cancer diagnosis in North American men but this was not statistically significant (OR 0.67, 95% CI 0.42–1.07, p = 0.091). Conclusions Phosphodiesterase type 5 inhibitor 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 phosphodiesterase type 5 inhibitor, this treatment was associated with an inverse trend of prostate cancer diagnosis that approached but did not reach statistical significance.