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 (0, 1, 2, and 3 or 4 conditions) with breast density.
Results
Among individual metabolic conditions, only high blood cholesterol was inversely associated with percent density (β=-5.4, 95% 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 2 conditions and 3 or 4 conditions vs. 0 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 cm2 (95% CI: -13.1, -0.1) and 9.5 cm2 (95% CI: -17.1, -1.9) smaller 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.