Statin use and breast cancer survival: A Swedish nationwide study

Background A sizeable body of evidence suggests that statins can cease breast cancer progression and prevent breast cancer recurrence. The latest studies have, however, not been supportive of such clinically beneficial effects. These discrepancies may be explained by insufficient power. This considerably sized study investigates the association between both pre- and post-diagnostic statin use and breast cancer outcome. Methods A Swedish nation-wide retrospective cohort study of 20,559 Swedish women diagnosed with breast cancer (July 1 st , 2005 through 2008). Dispensed statin medication was identified through the Swedish Prescription Registry. Breast cancer related death information was obtained from the national cause-of-death registry until December 31 st , 2012. Cox regression models yielded hazard ratios (HR) and 95% confidence intervals (CI) regarding associations between statin use and breast cancer-specific and overall mortality. Results During follow-up, a total of 4,678 patients died, of which 2,669 were considered breast cancer related deaths. Compared to non- or irregular use, regular pre-diagnostic statin use was associated with lower risk of breast cancer related deaths (HR=0.77; 95% CI 0.63–0.95, P=0.014). Similarly, post-diagnostic statin use compared to non-use was associated with lower risk of breast cancer related deaths (HR=0.83; 95% CI 0.75–0.93, P=0.001). Conclusion This study evidently supports the notion that statin use is protective regarding breast cancer related mortality in agreement with previous Scandinavian studies, although less so with studies in other populations. These disparities should be further investigated to pave the way for future clinical trials investigating the role of statins in breast cancer.