Spironolactone use does not increase the risk of female breast cancer recurrence: A retrospective analysis.

BACKGROUND: Spironolactone is used off-label for androgenic alopecia because of its ability to arrest hair loss progression and long-term safety profile. However, little is known about the safety of spironolactone in breast cancer (BC) survivors. Because spironolactone has estrogenic effects, there is a theoretical risk for BC recurrence. Given that spironolactone is an important tool in the treatment of alopecia, we investigated whether spironolactone increased risk for BC recurrence. OBJECTIVE: To determine whether spironolactone is associated with increased BC recurrence. METHODS: A retrospective analysis was conducted using the Humana Insurance database. Patients with a history of BC were identified using International Classification of Diseases codes, stratified by spironolactone prescription, and also matched 1:1 using propensity score analysis. Patient characteristics and cancer recurrence rates between both cohorts were compared and analyzed. RESULTS: BC recurrence developed in 123 patients (16.5%) who were prescribed spironolactone compared with 3649 patients (12.8%) who developed BC recurrence without spironolactone prescribed (P = .004). After propensity matching, adjusted Cox regression analysis showed no association between spironolactone and increased BC recurrence (adjusted hazard ratio, 0.966; 95% confidence interval, 0.807-1.156; P = .953). LIMITATIONS: Retrospective study. CONCLUSION: Spironolactone was not independently associated with increased BC recurrence and may be considered for the treatment of alopecia in BC survivors.