AB066. SOH24AB_029. The associations between breast density and body fat distribution: a cohort study

Background: There are known associations between breast composition and breast cancer risk. Breast density (BD) gives a reliable reflection of breast composition. Breast composition is highly variable and is influenced by many factors including adiposity, which is inversely associated with BD when measured as body mass index (BMI). However, body fat distribution (BFD) appears to be a more accurate measure of adiposity and metabolic health. This study examined the association between BD and BFD. Methods: Participants were retrospectively selected from a database of breast cancer patients. BD was categorised from mammograms. Subcutaneous fat area (SFA) and visceral fat area (VFA) was measured from abdominal computed tomography (CT) scans using CoreSlicer morphomics software. BMI was collected for comparison. Confounders were collected on chart review. Results: Forty-seven participants were included. All measures of adiposity were independently associated with BD. Associations were significant for BMI (P=0.027) and VFA (P=0.041), but not for SFA (P=0.065). When adjusted for covariates, SFA was inversely associated with BD (P=0.017) and VFA became directly associated with BD (P=0.005). History of fertility treatment and oral contraceptive use were positively associated with higher BD (P=0.002; P=0.006). Postmenopausal women were less likely to have a higher BD than premenopausal women (P=0.002). Conclusions: Quantification of adiposity as BFD revealed that SFA and VFA have opposing associations with BD. Menopause status has a significant association with BD. Further research is required to clarify these associations between BD and BFD.