Results:

Both cases and controls had similar distributions of age and annual household income and histories of hypertension, heart disease, and hypercholesterolemia. Compared with control women and IDC case patients, ILC case patients were somewhat less likely to be African American, more likely to be college graduates, and less likely to be obese (body mass index ≥30.0 kg/m²). Both IDC and ILC case patients were somewhat more likely to have a first-degree family history of breast cancer, to be current alcohol users, and to be current smokers. The proportion of current users of combined estrogen and progestin menopausal hormone therapy was highest among ILC case patients, intermediate among IDC case patients, and lowest among controls. Current use of calcium-channel blockers for 10 or more years was associated with higher risks of IDC (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.2-4.9; p = 0.04 for trend) and ILC (OR, 2.6; 95% CI, 1.3-5.3; p = 0.01 for trend). This relationship did not vary appreciably by type of calcium-channel blocker used (short-acting vs. long-acting, dihydropyridines vs. nondihydropyridines). In contrast, use of diuretics, beta-blockers, and angiotensin II antagonists were not associated with risk.