Abstract PO-178: Metabolic syndrome and risk of breast cancer by molecular subtype: Analysis of the Mechanisms for Novel and Established Risk Factors for Breast Cancer in Women of Nigerian Descent (MEND) study

Abstract

Abstract Background: The African continent experiences the highest age-standardized breast cancer mortality globally, with Nigeria reporting the highest rate within the continent. Breast cancer in Nigeria is characterized by several striking epidemiological features. These cancers are disproportionately pre-menopausal, diagnosed at late-stages with high-grade disease, and characterized by the highly-aggressive triple-negative subtype. However, few studies have focused on understanding the differentially patterned risk factors associated with high breast cancer burden among Nigerian women. Metabolic syndrome is characterized by a cluster of biological irregularities and is known to be a significant predictor of breast cancer incidence. The purpose of this analysis was to examine the association of metabolic syndrome with breast cancer and molecular subtypes among Nigerian women for first time. Methods: Metabolic syndrome was defined as having at least 3 out of 5 of: high blood pressure (≥130/85 mm Hg), reduced HDL (<50 mg/dL), elevated triglyceride (>150 mg/dL), high waist circumference (≥80 cm), and prior diagnosis of diabetes or elevated fasting glucose level (≥100 mg/dL). Among 296 newly diagnosed breast cancer cases and 259 healthy controls, multivariable logistic regression models were utilized to estimate adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for the association between metabolic syndrome and breast cancer overall. Multinomial logistic regression models were used to evaluate each molecular subtype (Luminal A, Luminal B, HER2-enriched and triple-negative). Results: Cases compared to controls were significantly more likely to have metabolic syndrome (30% vs. 17%; p<0.001). After adjusting for age, socio-demographic and reproductive risk factors, there was a positive association between metabolic syndrome and breast cancer (aOR: 1.84, 95% CI: 1.07, 3.16). In stratified analyses, metabolic syndrome was associated with breast cancer regardless of BMI status; however, the estimate was significant only among normal weight women (aOR: 3.85; 95% CI: 1.25, 11.90). Metabolic syndrome was significantly associated with the triple-negative breast cancer subtype (aOR: 4.37, 95% CI: 1.67, 11.44); associations for other molecular subtypes were not statistically significant. Conclusions: Metabolic syndrome appears to be a robust risk factor for breast cancer, particularly for triple-negative breast cancer. Public health and clinical interventions can provide substantial benefits in reducing the burden of metabolic syndrome and preventing breast cancer among Nigerian women. Citation Format: Tomi Akinyemiju. Metabolic syndrome and risk of breast cancer by molecular subtype: Analysis of the Mechanisms for Novel and Established Risk Factors for Breast Cancer in Women of Nigerian Descent (MEND) study [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-178.