Importance: Statin use has been associated with improved survival in patients with breast cancer, but there are no data on the association between statin use and survival in different intrinsic breast cancer subtypes. Objective: To assess the associations between statin use and survival in patients with early breast cancer of different intrinsic subtypes. Design, Setting, and Participants: A retrospective population-based cohort study of female patients with invasive breast cancer diagnosed in Finland between 1995 and 2013. The cohort was limited to early breast cancer cases with sufficient data for surrogate intrinsic subtyping. All data originated from Finnish national registries. Statistical analyses were performed from September to November 2023. Exposure: Statin use, statin dose, and blood cholesterol levels before and after diagnosis. Main Outcomes and Measures: All-cause and breast cancer-specific mortality during follow-up. Results: A total of 7389 female patients with early breast cancer were included (median range age at diagnosis, 60 21-102 years). Prediagnostic statin use was not associated with breast cancer-specific or all-cause mortality. Postdiagnostic statin use was associated with lower age-adjusted breast cancer-specific (hazard ratio HR, 0.68; 95% CI, 0.57-0.82) and all-cause (HR, 0.83; 95% CI, 0.75-0.92) mortality. In a multivariable-adjusted model, statin use was associated with higher breast cancer-specific survival in all hormone receptor-positive subtypes (luminal A-like, luminal B-like HER2-negative, and luminal B-like HER2-positive). All-cause mortality was lower among statin users in patients with hormone positive and triple-negative subtypes. One-year lag-time analysis or adjustment for blood-cholesterol levels after breast cancer diagnosis did not affect the results substantially. While the benefit of statin use was noticed in all statin users regardless of dose intensity, a trend of dose-dependent risk reduction was observed regarding breast cancer-specific mortality. Conclusions and Relevance: In this cohort study of patients with early breast cancer, prediagnostic statin use was not associated with higher survival; however, postdiagnostic statin use was associated with lower all-cause and breast cancer-specific mortality among patients with hormone receptor-positive intrinsic subtypes. These findings suggest that statin therapy may improve survival of patients with early hormone receptor-positive subtypes.
Palmi et al. (Tue,) studied this question.