We investigated the relationship between mammary gland volume (MGV) of the breast as measured with three-dimensional chest computed tomography (CT) and breast cancer risk. Univariate analysis was used to assess the relationship between MGV and known risk factors in 427 healthy women. A case control study (97 cases and 194 controls) was conducted to assess breast cancer risk.

MGV was significantly smaller for postmenopausal women than for premenopausal women, and was significantly larger for women with a family history of breast cancer than for women without. MGV, body mass index (BMI), and rate of family history of breast cancer were significantly higher among breast cancer patients than among healthy women, and number of deliveries was significantly lower among breast cancer patients. In postmenopausal women, age at menarche was significantly younger for breast cancer patients. MGV correlated well with breast cancer risk factors. The highest odds ratio was 4.9 for premenopausal women with the largest MGV. Regardless of menopausal status, the greater the MGV, the higher the odds ratio. Our results constitute the first reliable data on the relationship between MGV and breast cancer obtained through exact volume analysis.