Statins and breast cancer stage and mortality in the Women's Health Initiative.

Abstract

To evaluate the association between statins and breast cancer stage and mortality in the Women's Health Initiative. The study population included 128,675 postmenopausal women aged 50-79 years, out of which there were 7,883 newly diagnosed cases of in situ (19%), local (61%)-, regional (19%)- and distant (1%)-stage breast cancer and 401 deaths due to breast cancer after an average of 11.5 (SD = 3.7) years of follow-up. Stage was coded using SEER criteria and was stratified into early (in situ and local)- versus late (regional and distant)-stage disease. Information on statins and other risk factors were collected by self- and interviewer-administered questionnaires. Cause of death was based on medical record review. Multivariable-adjusted hazards ratios (HR) and 95% confidence intervals (CIs) evaluating the relationship between statin use (at baseline only and in a time-dependent manner) and diagnosis of late-stage breast cancer and breast cancer-specific mortality were computed from Cox proportional hazards analyses after adjusting for appropriate confounders. Statins were used by 10,474 women (8%) at baseline. In the multivariable-adjusted time-dependent model, use of lipophilic statins was associated with a reduction in diagnosis of late-stage breast cancer (HR 0.80, 95% CI 0.64-0.98, p = 0.035) which was also significant among women with estrogen receptor-positive disease (HR 0.72, 95% CI 0.56-0.93, p = 0.012). Breast cancer mortality was marginally lower in statin users compared with nonusers (HR 0.59, 95 % CI 0.32-1.06, p = 0.075). Prior statin use is associated with lower breast cancer stage at diagnosis.