The Association of 5-α Reductase Inhibitors for Benign Prostatic Hyperplasia With Development of Male Breast Disease...

To evaluate the association of 5-α reductase inhibitors (5ARIs; finasteride and dutasteride) with male breast cancer (MBC), gynecomastia, and erectile dysfunction (ED) among men treated for benign prostatic hyperplasia (BPH).

We queried the TriNetX database-Research Network. The exposure of interest was 5ARI. We propensity score matched (PSM) for demographic features, comorbidities, and MBC risk factors. Outcomes included risk of MBC, gynecomastia and ED.

5-ARI cohort (N = 553,628) and non-5ARI cohort (N = 2,729,063) before PSM and 550,622 patients in each cohort after. Follow-up of median 2.95 years and interquartile range (IQR) of 5.14 years in the 5ARI cohort versus median 2.94 years (IQR:5.44) in the non-5ARI cohort. Patients in the 5ARI cohort were not associated with a increased risk of MBC (RR 1.09; 95%CI:0.94-1.27). There was an increased risk of gynecomastia (RR 1.55, 95%CI:1.49-1.62) and ED (RR 1.17, 95%CI:1.15-1.18) associated with the use of 5ARI. On subgroup analysis, both finasteride (RR 1.12; 95%CI: 0.96-1.32) and dutasteride (RR 0.94; 95%CI: 0.67-1.32) were not associated with MBC. Both finasteride and dutasteride were associated with an increased risk of gynecomastia and ED, with stronger associations observed for dutasteride (gynecomastia: RR 2.13, 95% CI:1.92-2.35; ED: RR 1.40, 95% CI:1.35-1.45) than finasteride (gynecomastia: RR 1.48, 95% CI:1.42-1.54; ED: RR 1.14, 95% CI:1.12-1.15).

In this multi-institutional retrospective cohort study, we did not find an increased risk of MBC associated with 5ARI use.