Central adiposity after breast cancer diagnosis is related to mortality in the Health, Eating, Activity, and Lifestyle study

We examined whether waist circumference (WC) and waist-to-hip ratio (WHR) after breast cancer diagnosis are associated with all-cause or breast cancer-specific mortality and explored potential biological pathways mediating these relationships. Our analysis included 621 women diagnosed with local or regional breast cancer who participated in the Health, Eating, Activity, and Lifestyle study. At 30 (+/- 4) months postdiagnosis, trained staff measured participants' waist and hip circumferences and obtained fasting serum samples for biomarker assays for assays of insulin, glucose, C-peptide, insulin growth factor-1 and binding protein-3, C-reactive protein (CRP), and adiponectin. We estimated multivariate hazard ratios (HR) and 95 % confidence intervals (CI) for death over similar to 9.5 years of follow-up. After adjustment for measured body mass index, treatment, comorbidities, race/ethnicity, diet quality, and postdiagnosis physical activity, WC was positively associated with all-cause mortality (HRq4:q1: 2.99, 95 % CI 1.14, 7.86) but its positive association with breast cancer-specific mortality was not statistically significant (HRq4:q1: 2.69, 95 % CI 0.69, 12.01). WHR was positively associated with all-cause mortality (HRq4:q1: 2.10, 95 % CI 1.08, 4.05) and breast cancer-specific mortality (HRq4:q1: 4.02, 95 % CI 1.31, 12.31). After adjustment for homeostatic model assessment (HOMA) score and C-reactive protein, risk estimates were attenuated and not statistically significant. In this diverse breast cancer survivor cohort, postdiagnosis WC and WHR were associated with all-cause mortality. Insulin resistance and inflammation may mediate the effects of central adiposity on mortality among breast cancer patients.