Women who took tamoxifen for breast cancer had a 60% decreased risk of developing ischemic heart disease during 5 years of treatment, compared with women who had other cancers not treated with tamoxifen, Brian D. Bradbury, D.Sc., and his colleagues reported.
The large case-control study supports other recent studies showing that tamoxifen has a beneficial effect on low-density lipoprotein and total cholesterol levels in postmenopausal women taking the drug.
Dr. Bradbury of Boston University School of Public Health and his associates based their analysis on data derived from the United Kingdom's General Practice Research Database. Since 1987, more than 3 million U.K. residents have been enrolled in the database (Cancer 2005;103:1114-21).
The researchers matched 3,030 women aged 30-85 years with a first-time diagnosis of breast cancer treated with tamoxifen with 4,233 controls who had other cancers (bladder, colorectal, and nonmelanoma skin cancer). Women with a history of heart attack, angina pectoris, and HIV/acquired immunodeficiency syndrome were excluded. The median follow-up for all women was about 2 years. Of a total of 154 cases of ischemic heart disease, women with breast cancer had a reduced rate of heart disease, compared with women with the other cancers (hazard ratio=0.5).
The investigators then matched 585 of the controls to 151 of the women with heart disease. The women with heart disease were more likely to be obese, to be former smokers, and to have been treated for hypertension, compared with the controls. Current use of tamoxifen was associated with a 60% decreased risk of heart disease. When myocardial infarction and angina were assessed separately, the decreased risk for current tamoxifen users was 80% for MI and 60% for treated angina.
The protective effect lasted throughout the 5-year treatment period, with a 60% decreased risk for the first 4 years and a 50% decreased risk thereafter.