Statins reduce breast cancer risk: a case control study in US female veterans

Authors: R. Kochhar, V. Khurana, H. Bejjanki, G. Caldito, C. Fort


Background: Statins (HMG CoA reductase inhibitors) are commonly used cholesterol-lowering agents that are noted to suppress tumor growth in several animal models, however clinical data for chemoprotective role of statins in breast cancer is conflicting. While some studies report reduced risk of breast cancer with lipid lowering drugs, others report an increased risk. We investigated the effect of statins on the development of breast cancer in the US female veteran population.

Methods: The VISN 16 database, which contains clinical and demographic information about all veterans (>1.4 million patients) cared for in the South Central VA Health Care Network, was queried from Oct 1998 to June 2004. Retrospective case control design was used. Patients were placed in the statin users group if they were taking statins prior to the diagnosis of breast cancer but the dose, duration and type of statin used was not factored into the analysis. Statistical analysis was performed using SAS software version 9.0 (Chicago, IL). Multiple logistic regression analysis was used with calculation of odds ratios and 95% confidence intervals. The data was adjusted for age, smoking, alcohol use and diabetes.

Results: A total of 40,421 women were studied. The median age was 58 (range 25-92) years. 4771 (11.8%) were on statins. Breast cancer was seen in 556 (1.38%) women. Statin users were less likely to develop breast cancer (Odds ratio 0.49: 95% CI 0.38-0.62, p=<0.0001). The data was controlled for age (OR 1.051, 95% CI 1.045 -1.056, p=<0.0001), smoking (OR 1.82, 95% CI 1.25 -2.65, p=0.002), alcohol use (OR 1.87, 95% CI 1.56 -2.25, p=<0.0001), and diabetes (OR 1.83, 95% CI 1.46 -2.30, p=<0.0001). All these were significant covariates.

Conclusions: Statins are associated with a 51% risk reduction of breast cancer after controlling for age, smoking, alcohol use and diabetes. An internal consistency of the database is reflected by an increased risk associated with documented risk factors.