Does Spironolactone Raise Breast Cancer Risk?

Because gynecomastia is a common adverse effect of the aldosterone antagonist spironolactone, some clinicians avoid prescribing this drug to women out of concern that exposure might raise risk for breast cancer. U.K. investigators conducted a retrospective cohort study that involved 1.3 million women without histories of breast cancer to determine whether exposure to spironolactone was associated with excess risk for breast cancer. The exposed cohort consisted of 28,000 older women (age, >55) who received ≥2 prescriptions for spironolactone (half received ≥12 prescriptions). Exposed patients were matched by age and socioeconomic status to nearly 56,000 unexposed controls.

After a mean follow-up of 4 years, both the exposed and unexposed coho…