Objective: To evaluate the associations of body composition, including percentage of lean and fat mass, with the percentage of mammographic density and mammographic dense area among pre- and postmenopausal Hispanic and non-Hispanic white women.
Design: In this cross-sectional study, a total of 238 women aged 41 to 50 or 56 to 70 years were recruited from local mammography clinics and community health centers. Postmenopausal status was defined as an absence of any menstrual cycle within the past 12 calendar months or having a follicle-stimulating hormone level between 22 and 138 mIU/mL. The participants' most recent mammograms were used for the mammographic density analysis. Body composition was measured by dual-energy x-ray absorptiometry. The associations between the percentage of mammographic density or mammographic dense area and body composition components were analyzed using logistic regression.
Results: Mammographic dense areas were similar in Hispanic and non-Hispanic white women. The percentage of mammographic density varied by ethnicity in premenopausal (P = 0.023), but not in postmenopausal women. Body composition, both higher lean mass and lower fat mass, was associated with a higher percentage of mammographic density (P < 0.05). Interestingly, a higher percentage of total body fat mass and a lower percentage of total body lean mass were correlated with larger breast dense areas in premenopausal women but with lower breast dense areas in postmenopausal women. These relationships between body composition and mammographic density measurements were not significantly affected by factors such as age, ethnicity, and body weight.
Conclusions: Body composition is highly correlated with mammographic density and should be examined as a possible confounding factor in studies involving mammographic density measurements and breast cancer risk.