Finasteride Treatment and Male Breast Cancer: A Register-Based Cohort Study in Four Nordic Countries

December 2017 in “ Cancer Medicine ”

Mathias Meijer, Lau Caspar Thygesen, Anders Green, Martha Emneus, Klaus Brasso, Peter Iversen, Eero Pukkala, Kristian Bolin, Knut Stavem, Annette Kjær Ersbøll

finasteride male breast cancer MBC incidence rate ratio IRR Propecia

Studysummary This study found an association between dispensed finasteride and an increased risk of male breast cancer, though uncertainties around confounding factors and potential biases suggest these results should be interpreted with caution. Our plain-language summary of this paper — not a Tressless recommendation.

The study analyzed the link between finasteride use and male breast cancer (MBC) in a cohort from Denmark, Finland, Norway, and Sweden, with 1,365,088 person-years of follow-up. It found a 44% increased risk of MBC among finasteride users, with an incidence rate ratio (IRR) of 1.44. The risk was even higher, with an IRR of 1.60, when excluding users from Norway and Sweden with short follow-up times. The greatest risk was seen in men with medium duration of use and those who started finasteride 1-3 years before diagnosis. The study noted potential biases and recommended further research due to limitations such as possible ascertainment bias and the inability to adjust for all confounding factors. Despite these limitations, the study suggested an increased risk of MBC with finasteride use, especially in Denmark and Finland.

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Research cited in this study

5 / 5 results

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research The Effect of Finasteride on the Risk of Acute Urinary Retention and the Need for Surgical Treatment Among Men with Benign Prostatic Hyperplasia

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