Male breast cancer and 5α-reductase inhibitors finasteride and dutasteride

J Urol. 2013 Nov;190(5):1811-4. doi: 10.1016/j.juro.2013.04.132. Epub 2013 May 9.


Purpose: We examined the association between 5α-reductase inhibitors and male breast cancer.

Materials and methods: Study participants were men 40 to 85 years old, with prescription and medical coverage, enrolled in the United States IMS LifeLink™ Health Plan claims database between 2001 and 2009. Cases required a primary breast cancer diagnosis (ICD-9-CM 175.x) on 2 different dates and a procedural code for mastectomy or lumpectomy/partial mastectomy with evidence of continuous care (radiation/chemotherapy or diagnoses in 2 or more months). Eligible controls were within 5 years in age and had duration of prior health care enrollment within 6 weeks. Risk set sampling selected 20 controls per case. We assessed the rate ratio for male breast cancer with 5α-reductase inhibitor exposure using conditional logistic regression. Analyses were stratified by duration of health care enrollment before diagnosis (1 year or more, 2 years or more and 3 years or more), each incremental 180 and 365 days of cumulative 5α-reductase inhibitor exposure, and period specific time frames before diagnosis (years 1, 2 and 3).

Results: We identified 339 breast cancer cases matched to 6,780 controls. No statistically significant associations were observed between 5α-reductase inhibitors and breast cancer regardless of exposure assessment before the index date (1 year or more-RR 0.70, 95% CI 0.34-1.45; 2 years or more-RR 0.59, 95% CI 0.24-1.48; or 3 years or more-RR 0.75, 95% CI 0.27-2.10). Each subsequent 180 days (RR 1.02, 95% CI 0.67-1.53) and 365 days (RR 1.03, 95% CI 0.45-2.37) of cumulative 5α-reductase inhibitor therapy and period specific rate ratios also showed null associations.

Conclusions: The lack of an association in our study suggests that the development of breast cancer should not influence the prescribing of 5α-reductase inhibitor therapy.

Keywords: 5-alpha reductase inhibitors; 5ARI; 5α-reductase inhibitor; FDA; Food and Drug Administration; PPV; breast neoplasms; male; positive predictive value.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-alpha Reductase Inhibitors / adverse effects*
  • Adult
  • Aged
  • Aged, 80 and over
  • Azasteroids / adverse effects*
  • Breast Neoplasms, Male / chemically induced*
  • Breast Neoplasms, Male / epidemiology*
  • Dutasteride
  • Finasteride / adverse effects*
  • Humans
  • Male
  • Middle Aged


  • 5-alpha Reductase Inhibitors
  • Azasteroids
  • Finasteride
  • Dutasteride