Cholesterol lowering drug use and breast cancer survival: the Multiethnic Cohort Study

PURPOSE: Prior studies conducted primarily in white populations have suggested that pre-diagnostic cholesterol lowering drugs (CLDs) improved survival among women with breast cancer (BC). However, this association had not been well characterized in diverse racial/ethnic populations. We investigated whether pre-diagnostic CLD use is associated with all-cause and BC-specific mortality among female BC cases of the Multiethnic Cohort (MEC). METHODS: CLD use was ascertained through questionnaires administered in 2003–2008. A total of 1448 incident BC cases were identified by linkage to SEER cancer registries in Hawaii and California from 2003 to 2014. Multivariable Cox regression was conducted to estimate hazard ratios (HR) and 95% confidence intervals (CI) of the associations of pre-diagnostic CLD use with all-cause and BC-specific mortality, adjusting for tumor characteristics, first course of treatment, health behaviors, co-morbidities, and demographics. Subgroup analyses by stage and hormone receptor status were conducted for all-cause mortality. RESULTS: There were 224 all-cause and 87 BC-specific deaths among the 1448 BC cases during a median follow-up of 4.5 years after diagnosis. Women with BC who ever used CLDs had a 27% lower hazard of all-cause mortality (HR 0.73, 95% CI 0.54–0.98) and 17% lower hazard of BC-specific mortality (HR 0.83, 95% CI 0.49–1.39) compared to never users. CLD use reduced mortality among women with advanced-stage tumors and hormone receptor-positive breast tumors (HR 0.54 95% CI 0.33–0.90; HR 0.69, 95% CI 0.48–0.99, respectively). CONCLUSION: These findings demonstrate an improved survival associated with CLD use prior to diagnosis in a multiethnic population of women with BC. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10549-021-06360-y.