ASSOCIATION BETWEEN HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL AND BREAST-CANCER VARIES BY MENOPAUSAL STATUS

A nested case-control study was conducted to investigate the hypothesi s that women with high levels of high-density lipoprotein cholesterol (HDL-C) are at an increased risk of breast cancer. The source populati on was a cohort of 95,000 women enrolled in the Raiser Permanente Medi cal Care Program who underwent a routine multiphasic health examinatio n between 1964 and 1971, From the more than 2,000 breast cancer cases diagnosed in this cohort, 200 cases were randomly selected for this st udy. For each case, one control who matched on age and date of examina tion was chosen. Lipid and lipoprotein levels were measured in archive d serum samples collected at the time of the women's examinations. Bre ast cancer risk factor information was obtained from questionnaires co mpleted by the women when their blood was drawn and was supplemented w ith information from medical records. HDL-C levels were not significan tly different between the cases and controls overall; however, a stati stically significant interaction between the HDL-C level and menopausa l status at diagnosis was detected. Premenopausal cases had mean HDL-C levels 3.48 mg/dl lower than matched controls [95% confidence interva l (CI), -7.05, 0.09], whereas postmenopausal cases had levels 2.05 mg/ dl higher than controls (95% CI, -0.94, 5.03), In multivariate conditi onal logistic regression analyses, the odds ratio associated with each 1 mg/dl increase in HDL-C was 0.96 (95% CI, 0.93-1.0) for premenopaus al women and 1.02 (95% CI, 0.99-1.05) for postmenopausal women. Althou gh many breast cancer risk factors are associated with high HDL-C, the relationship between breast cancer and HDL-C was independent of other factors evaluated.