Statin Use and Breast Cancer Risk in a Large Population-Based Setting

Abstract

Background: Mechanistic studies suggest that 3-hydroxy-3-methylglutaryl CoA inhibitors (statins) reduce the risk of breast cancer. Observational studies offer mixed results. Methods: To evaluate the relation between statin use and breast cancer risk, we conducted a cohort study among women ages 45 to 89 years within an integrated health care delivery system. Information on statin use and covariates were obtained from automated databases. We identified breast cancer cases through the Surveillance, Epidemiology, and End Results registry. We used Cox proportional hazards models to estimate the hazard ratios (HR) and 95% confidence intervals (95% CI) for invasive breast cancer among statin users compared with nonusers. Results: Among 92,788 women studied from 1990 to 2004, median follow-up time was 6.4 years, and 2,707 breast cancer cases were identified. During the study period, 7.4%

Estrogen Receptor–Negative Breast Cancer Is Less Likely to Arise among Lipophilic Statin Users

“…Only two studies have investigated the effect of statins on specific histologic type. At first glance, our results seem to be at odds with two large retrospective studies (Nurses' Health Study and Group Health of Western Washington State), which report data on statin use and breast cancer phenotype by ER (16,18). The disputed results may be explained by inclusion of both lipophilic and hydrophilic (that is, pravastatin) in their analysis of statin use on ER.…”

“…Based on this evidence, we explored the possibility that lipophilic statin users among a cohort of (7,8,(15)(16)(17), we adopted a pharmacologic classification widely used by cardiovascular researchers in which pravastatin and rosuvastatin are considered hydrophilic statins, whereas other approved statins are considered lipophilic (28,29).…”

“…Most recently, a large cohort study by Boudreau et al designed to evaluate statin use and breast cancer risk failed to identify any significant risk reduction benefit among lipophilic statin users z1 year (HR, 1.07; 95% CI, 0.88-1.29) compared with nonusers and likewise found no significant benefit according to type of statin used or reduction in the specific risk of developing receptornegative breast cancer (16). However, although powered to address breast cancer risk reduction on statins, the study by Boudreau et al may not have been sufficiently powered to discern a statin-induced decline in the number of newly diagnosed receptor-negative breast cancers.…”

“…Additionally, data from three large retrospective studies and one large prospective study were not included in these metaanalyses, as they had not yet been published. Analysis of retrospective data through the Nurses' Health Study by Eliassen et al (n = 75,828) as well as a large retrospective population-based study by Boudreau et al (n = 92,788) found no difference in breast cancer risk with statin use (15,16). However, one retrospective study of 40,421 women found a protective benefit of statins (relative risk, 0.49) that increased with increasing duration of statin use (17).…”

Statin use and prostate cancer risk in a large population-based setting

“…We previously published results on the association between statin use and breast cancer risk using a similar methodology as described below [29].…”