Breast cancer and spironolactone: an observational postmarketing study

Recent studies have discussed the risk of breast cancer with antihypertensive drugs. For spironolactone, data are conflicting. The present paper investigates this potential signal in VigiBase^®, the World Health Organization Global Individual Case Safety Report (ICSR) database.

In VigiBase^®, we performed a case/non-case study using data registered from 1981 (spironolactone's marketing authorization) to December 31, 2017. Among women ≥ 50 years, we measured the risk of reporting "Breast malignant tumors" compared with all other adverse drug reactions (as a crude and adjusted (a) reporting odds ratio (ROR 95% CI)) for spironolactone compared with first, all other drugs and second, pseudo aldosterone antagonists (amiloride, triamterene). ROR were adjusted for age, year of report, continent of report, number of drug prescribed, and completeness score. Sensitivity analyses were performed after exclusion of drug competitors (i.e., drugs like estroprogestative therapy and progestogens that could mask a putative signal) and reports from health professionals.

During the study period, 125 ICSRs reported spironolactone exposure and breast malignant cancer in women ≥ 50 years. We failed to find a positive association between spironolactone exposure and breast cancer in comparison with exposure to other drugs (aROR = 0.63 95% CI [0.52-0.75]) or pseudo aldosterone antagonists (amiloride, triamterene) (0.56 [0.44-0.72]). Similar trends were found after exclusion of drug competitors and/or reports from health professionals.

This study did not find evidence for breast cancer associated with spironolactone.