UC Irvine

PURPOSE: We examined whether obesity and a history of diabetes, hypertension, and elevated cholesterol, individually and in combination, are associated with breast density, a strong risk factor for breast cancer. METHODS: We measured percent density and dense area using a computer-assisted method (n = 191; age range = 40-61 years). We used linear regression models to examine the associations of each metabolic condition and the number of metabolic conditions (zero, one, two, and three or four conditions) with breast density. RESULTS: Among individual metabolic conditions, only high blood cholesterol was inversely associated with percent density (β = -5.4, 95% confidence interval [CI]: -8.5, -2.2) and dense area (β = -6.7, 95% CI = -11.1, -2.4). Having multiple metabolic conditions was also associated with lower breast density, with two conditions and three or four conditions versus zero conditions associated with 6.4% (95% CI: -11.2, -1.6) and 7.4% (95% CI: -12.9, -1.9) reduction in percent density and with 6.5 cm(2) (95% CI: -13.1, -0.1) and 9.5 cm(2) (95% CI: -17.1, -1.9) decrease in dense area. CONCLUSIONS: A history of high blood cholesterol and multiple metabolic conditions were associated with lower relative and absolute measures of breast density. The positive association between metabolic abnormalities and breast cancer risk may be driven by pathways unrelated to mammographic breast density.