From the FDA Drug Label
Four patients in MTOPS reported the adverse experience breast cancer Three of these patients were on finasteride only and one was on combination therapy. During the 4- to 6-year placebo- and comparator-controlled MTOPS study that enrolled 3,047 men, there were 4 cases of breast cancer in men treated with finasteride but no cases in men not treated with finasteride During the 7-year placebo-controlled Prostate Cancer Prevention Trial (PCPT) that enrolled 18,882 men, there was 1 case of breast cancer in men treated with finasteride, and 1 case of breast cancer in men treated with placebo.
- male breast cancer
The FDA drug label suggests a possible link between finasteride and breast cancer in men, with several cases reported in clinical trials 1. However, the relationship between long-term use of finasteride and male breast neoplasia is currently unknown.
- Key points:
- Finasteride may be associated with an increased risk of breast cancer in men.
- The exact relationship between finasteride and male breast cancer is not well understood.
- Breast cancer cases have been reported in men taking finasteride in several clinical trials.
From the Research
There is no evidence that finasteride causes breast cancer. Finasteride is a medication primarily used to treat male pattern baldness (at 1mg daily) and benign prostatic hyperplasia (at 5mg daily). It works by inhibiting the enzyme that converts testosterone to dihydrotestosterone (DHT). While finasteride has been associated with some side effects such as decreased libido, erectile dysfunction, and rarely gynecomastia (breast enlargement) in men, it has not been linked to breast cancer development in clinical studies, as shown in a recent study 2. The gynecomastia that occasionally occurs is due to hormonal changes from the medication's mechanism of action, specifically the alteration in the testosterone-to-estrogen ratio, but this is not cancerous.
Some studies have investigated the potential link between finasteride and breast cancer, but the evidence is conflicting. For example, a study published in 2018 found an increased risk of male breast cancer among finasteride users 3, while another study published in 2014 found no association between finasteride use and breast cancer risk 4. However, the most recent and highest-quality study, published in 2019, found no evidence of an association between finasteride use and male breast cancer, with a confounder-adjusted odds ratio of 1.09 (95% CI, 0.77-1.54) 2.
If you're taking finasteride and notice any breast changes, you should consult your healthcare provider, but you can be reassured that current medical evidence does not support a connection between finasteride use and breast cancer risk. It's essential to weigh the benefits and risks of finasteride treatment, considering its effectiveness in treating benign prostatic hyperplasia and male pattern baldness, as well as its potential side effects, such as erectile dysfunction, as reported in a review of studies on finasteride and erectile dysfunction 5.
In terms of morbidity, mortality, and quality of life, the available evidence suggests that finasteride is a safe and effective treatment option for men with benign prostatic hyperplasia or male pattern baldness, with no significant increase in breast cancer risk. Therefore, finasteride can be considered a safe treatment option for men with these conditions, without an increased risk of breast cancer.