Abstract B136: The association of estimated visceral adipose tissue amount with risk of postmenopausal breast cancer in the Multiethnic Cohort Study

Abstract Background: Visceral adipose tissue (VAT) has been shown to be a key contributor to breast cancer risk, particularly among postmenopausal women, independent of body mass index (BMI). Our prior work developing a biomarker-derived VAT score showed statistically a significant association with postmenopausal breast cancer incidence. However, biomarker-based and/or imaging may not be scalable for large studies or where resources are limited. Therefore, we aimed to assess whether an equation for estimating VAT (eVAT) based on age, weight, height, BMI, waist, and hip circumferences, developed in the UK Biobank and validated in NHANES among predominantly White populations predicts breast cancer risk in women of various race and ethnic groups. Methods: This study included 34,763 postmenopausal women followed since 2003-2008 as part of the Multiethnic Cohort (MEC). Cox proportional hazards models were used to estimate hazard ratios (HRs) for breast cancer and 95% confidence intervals (CIs). The model was adjusted for age, race/ethnicity (for overall model), education, smoking status, pack-years of smoking, family history of cancer and alcohol intake. Breast cancer cases were identified through linkages to statewide Hawaii and California SEER cancer registries. Results: During a mean follow-up of 6.9 years, 1,632 incident breast cancer cases (197 African American, 201 Native Hawaiian, 578 Japanese American, 227 Latino, and 429 White cases) were diagnosed. We observed a statistically significantly positive association between eVAT and breast cancer incidence. In the adjusted models, for every standard deviation increase in eVAT, breast cancer risk increased by 24% (HR: 1.24; 95% CI: 1.18-1.31). The HR was attenuated to 5% after further adjustment for BMI (HR 95% CI: 1.00-1.11). By race/ethnicity, Japanese Americans had the highest increase in incidence of breast cancer with an HR of 1.41 (95%CI: 1.28-1.56), followed by Native Hawaiians (HR 1.28; 95% CI: 1.13-1.44), Latinos (HR 1.24; 95% CI: 1.08-1.42), and White individuals (HR 1.18; 95%CI: 1.07-1.29). No significant association was found for African Americans (HR: 1.06 ; 95% CI: 0.92-1.21). Conclusion: These results confirm the important role of VAT in breast cancer etiology, in particular among Japanese American women, and may explain the observation that BMI confers a higher breast cancer risk in Japanese Americans than White populations. Citation Format: Janine V. Abe, Song-Yi Park, Gertraud Maskarinec, Samantha A. Streicher, Christopher A. Haiman, Lynne R. Wilkens, Loïc Le Marchand. The association of estimated visceral adipose tissue amount with risk of postmenopausal breast cancer in the Multiethnic Cohort Study [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr B136.