Finasteride Use and Risk of Male Breast Cancer: A Case-Control Study Using Individual-Level Registry Data from Denmark, Finland, and Sweden

In 2019, a large-scale study was conducted in Denmark, Finland, and Sweden involving 1,005 male breast cancer cases and 43,058 controls to investigate the potential link between finasteride use and male breast cancer. The results showed no statistically significant increase in the odds of finasteride exposure in breast cancer cases compared to controls. Even after accounting for potential confounders, the odds ratio for the association between finasteride use and male breast cancer decreased. The study concluded that there was no clear relationship between finasteride use and male breast cancer. Despite the large sample size, only 38 cases were exposed to finasteride, indicating that the drug, commonly used to treat hair loss and benign prostatic hyperplasia, was not materially associated with male breast cancer risk.