From the Guidelines
Spironolactone use is not associated with a significantly increased risk of breast cancer, with a relative risk of 1.04 and a 95% confidence interval of 0.86-1.22, as reported in a 2024 study 1. The current evidence suggests that spironolactone can be prescribed at typical doses (25-100 mg daily) without significant concern for breast cancer development.
- Key points to consider:
- The relative risk of breast cancer associated with spironolactone use is 1.04, which is not significantly different from 1, indicating no increased risk 1.
- The 95% confidence interval of 0.86-1.22 also supports the lack of association between spironolactone use and breast cancer risk 1.
- Patients taking spironolactone should be aware of potential side effects, including breast tenderness and enlargement in some individuals, which are generally reversible upon discontinuation of the medication.
- Important considerations for patient care:
- Patients with a personal or strong family history of breast cancer should discuss the use of spironolactone with their healthcare provider to weigh individual risks and benefits.
- Regular breast cancer screening as recommended for the general population should be continued while taking spironolactone. The lack of association with breast cancer is likely because spironolactone's anti-androgenic effects are relatively weak compared to other hormonal medications, as reported in the 2024 study 1.
From the Research
Spironolactone Use and Breast Cancer Risk
- The association between spironolactone use and breast cancer risk has been investigated in several studies 2, 3, 4, 5, 6.
- A systematic review and meta-analysis found no statistically significant association between spironolactone use and risk of breast cancer (risk ratio [RR], 1.04; 95% CI, 0.86-1.22) 2.
- A cohort study of Danish women found that the risk of breast cancer was not significantly increased with spironolactone use, and that any observed associations were likely due to reverse causality 3.
- A retrospective, matched cohort study in the UK found no evidence of an increased risk of breast cancer with spironolactone use, and actually found a lower risk of prostate cancer 4.
- An observational postmarketing study using the World Health Organization Global Individual Case Safety Report database found no positive association between spironolactone exposure and breast cancer in women over 50 years old 5.
- A retrospective, matched cohort study in the UK found no evidence of an increased incidence of breast cancer in women over 55 years old who were exposed to spironolactone 6.
Key Findings
- No significant association between spironolactone use and breast cancer risk has been found in multiple studies 2, 3, 4, 5, 6.
- The certainty of the evidence is generally low, and future studies are needed to confirm these findings 2.
- Spironolactone use has been associated with a decreased risk of prostate cancer in some studies 2, 4.