TLDR Taking 5-alpha reductase inhibitors does not increase breast cancer risk in men.
The systematic review analyzed 6 studies with a total of 137,421 subjects taking 5-alpha reductase inhibitors (5ARIs) and 568,469 control subjects to determine if there was an association between 5ARI use and breast cancer risk in men. The studies reviewed, which included randomized controlled trials, case-control studies, and cohort studies, found no evidence that 5ARIs, such as finasteride and dutasteride, increase the risk of breast cancer in men. Although the results showed variable risks, none were statistically significant. The authors suggested the need for further research to confirm these findings and to explore the effects of 5ARIs on the endocrine system.
28 citations,
August 2014 in “Cancer Causes & Control” Taking 5α-reductase inhibitors does not significantly increase the risk of breast cancer in men.
32 citations,
May 2013 in “The Journal of Urology” Using finasteride or dutasteride does not increase the risk of male breast cancer.
12 citations,
May 2010 in “PubMed” No definitive link between finasteride and male breast cancer, but further research is needed.
195 citations,
February 2007 in “The Journal of Clinical Endocrinology and Metabolism” Dutasteride and finasteride may reduce sperm count and volume but don't affect movement or shape; effects are reversible after stopping.
1707 citations,
December 2003 in “The New England Journal of Medicine” Combination therapy of doxazosin and finasteride safely and effectively reduces benign prostatic hyperplasia progression risk.
1054 citations,
February 1998 in “The New England Journal of Medicine” Finasteride reduces urinary issues and surgery need in men with enlarged prostates by over 50%.
31 citations,
September 2008 in “International Journal of Andrology” 5-alpha-reductase inhibitors may cause a low incidence of erectile dysfunction that decreases over time.
50 citations,
March 2017 in “PeerJ” Using finasteride or dutasteride may cause long-lasting erectile dysfunction.
January 2015 in “Side effects of drugs annual” The document concludes that sex hormones and related compounds have various effects on health, with both potential benefits and risks.
37 citations,
April 2008 in “The Cochrane library” 5-alpha-reductase inhibitors can lower prostate cancer risk but may increase high-grade tumors and cause sexual side effects.
2 citations,
March 2018 in “Current Opinion in Urology” 5-alpha reductase inhibitors can cause sexual, neurologic, endocrine, and cardiovascular side effects, but these are rare and usually stop after ending treatment.
