Statin use and the risk of breast and prostate cancer

Background. Laboratory data suggest that the cholesterol-lowering "statin" drugs may have chemopreventive potential against cancer at various sites, including breast and prostate. However, in one trial of pravastatin there was a significant excess of breast cancer in the treatment group. In the present study, we assessed the relation of statin use to the risk of breast and prostate cancer in our hospital-based Case-Control Surveillance Study of Drugs and Serious Illnesses. Methods. Cases were 1,132 women with breast cancer and 1,009 men with prostate cancer; controls were 1,331 women and 1,387 men admitted for conditions unrelated to statin use. We used multivariate unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for use of statins compared with no use. Results. The OR for breast cancer among statin users was 1.5 (95% CI = 1.0-2.3), largely accounted for by an OR of 1.8 (95% CI = 0.9-3.6) among cases with carcinoma in situ. Among invasive cases, the OR was 1.2 (95% CI = 0.7-2.0). The odds ratio for prostate cancer overall was 1.2 (95% CI = 0.8-1.7), and it was 1.4 (95% CI = 0.7-2.5) for Stage A. Conclusions. The data from the present study do not support a protective effect of statins against breast or prostate cancer. Detection bias is a possible explanation for the higher ORs observed for carcinoma in sim or early-stage cancer as compared with more invasive cancer.