De novo post-diagnosis statin use, breast cancer-specific and overall mortality in women with stage I–III breast cancer

Background: Prior evidence suggests a role for statins in the management of cancer. However, the benefit of statin use in the adjuvant setting remains uncertain. This study investigates associations between statin use initiated after a breast cancer diagnosis and mortality. Methods: Women with stage I–III breast cancer were identified from the National Cancer Registry of Ireland ( N =4243). Post-diagnostic statin initiators were identified from pharmacy claims data ( N =837). Multivariate models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between de novo statin use and mortality. Results: The median duration of statin use was 6.7 years. No association was found between post-diagnostic statin use and breast cancer-specific (HR 0.88, 95% CI 0.66, 1.17) or all-cause mortality (HR 1.00, 95% CI 0.82, 1.21). Conclusions: The results from our study suggest that initiating statin use after a diagnosis of stage I–III breast cancer is not associated with a reduction in breast cancer-specific mortality.