Is oral spironolactone (aldosterone antagonist) safe for treating alopecia in patients with a history of breast cancer?

From the Guidelines

Spironolactone is generally not recommended for treating alopecia in people with a history of breast cancer due to its potential to stimulate estrogen-dependent tissues, which may pose a theoretical risk for breast cancer recurrence or progression. For patients with a history of breast cancer who are experiencing hair loss, alternative treatments should be considered first. Some key points to consider include:

• The use of spironolactone in men and women above age 18 years has been associated with risks of various cancers, although the certainty of evidence is low to very low 1.
• The medication works as an anti-androgen, but its effects on estrogen-dependent tissues are a concern in patients with a history of breast cancer.
• Topical minoxidil (2% or 5%) is the safest first-line option, applied twice daily to affected areas, as it does not have the same theoretical risks as spironolactone.
• Other safer alternatives include low-level laser therapy devices, platelet-rich plasma injections, or non-hormonal oral options like oral minoxidil at low doses (0.25-2.5mg daily).
• If hormonal therapy is absolutely necessary, consultation with both an oncologist and dermatologist is essential before considering spironolactone, and the decision should be individualized based on the type of breast cancer, receptor status, time since diagnosis, current cancer treatment, and overall prognosis 1.
• Some oncologists may consider spironolactone in select cases of hormone receptor-negative breast cancers or in patients many years post-treatment with excellent prognosis, but this remains controversial and requires careful monitoring.

From the FDA Drug Label

In a 24-month study in which the same strain of rat was administered doses of about 10 mg, 30 mg, 100 mg, and 150 mg spironolactone/kg/day, the range of proliferative effects included significant increases in hepatocellular adenomas and testicular interstitial cell tumors in males, and significant increases in thyroid follicular cell adenomas and carcinomas in both sexes

• The FDA drug label does not directly address the use of oral spironolactone for alopecia in people with a history of breast cancer.
• Key points:
  • The label discusses the carcinogenic effects of spironolactone in animal studies, but does not provide information on its safety in patients with a history of breast cancer.
  • There is no direct information on the use of spironolactone for alopecia in patients with a history of breast cancer. The FDA drug label does not answer the question.

From the Research

Oral Spironolactone for Alopecia in People with a History of Breast Cancer

• The use of oral spironolactone for alopecia in people with a history of breast cancer has been studied in several research papers 2, 3, 4, 5.
• A retrospective analysis published in the Journal of the American Academy of Dermatology found that spironolactone use does not increase the risk of female breast cancer recurrence 2.
• The study analyzed data from the Humana Insurance database and found that breast cancer recurrence developed in 123 patients (16.5%) who were prescribed spironolactone, compared to 3649 patients (12.8%) who did not receive spironolactone 2.
• After propensity matching, the study found no association between spironolactone and increased breast cancer recurrence, with an adjusted hazard ratio of 0.966 (95% confidence interval, 0.807-1.156; P = .953) 2.
• Another study published in the Annals of Oncology found that permanent scalp alopecia can occur after breast cancer chemotherapy, and that treatment with spironolactone was ineffective in promoting hair regrowth 3.
• A review of published studies on the safety of 5α-reductase inhibitors and spironolactone in breast cancer patients receiving endocrine therapies found no evidence of interactions between these treatments and endocrine therapies used in breast cancer 4.
• The review also found that most patients did not have a significant alteration in estrogen levels when using spironolactone, and that there was no consistent evidence of increased risk of female breast cancer with spironolactone use 4.
• A retrospective cohort study published in JAMA Dermatology found that endocrine therapy-induced alopecia is a common side effect of breast cancer treatment, and that minoxidil can be an effective treatment for this condition 5.
• The study found that alopecia was attributed to aromatase inhibitors in 67% of patients and tamoxifen in 33%, and that the severity was grade 1 in 92% of patients 5.