Overall and Visceral Adiposity Are Associated with Incident Cardiovascular Disease among Breast Cancer Patients: Results from the B-SCANS Study

It is assumed that total and visceral adiposity increase cardiovascular disease (CVD) risk among breast cancer survivors; yet, these associations have not been studied, and could differ from non-cancer populations due to the modifying effects of cancer treatment. METHODS: We studied 2,630 Stage I–III breast cancer patients without pre-existing CVD diagnosed at Kaiser Permanente (2006–2013). We quantified body composition from computed tomography scans taken at breast cancer diagnosis. The main exposures were total and visceral adiposity indices (cm2/m2), examined in tertiles. From ICD codes, we identified non-fatal stroke, coronary artery disease (CAD), and heart failure, and a composite outcome including CVD death (CVD). We estimated hazard ratios (HR) and 95% confidence intervals (CI) adjusting for age, smoking, tumor (stage, grade, and ER/PR and HER2 status) and treatment (chemotherapy and/or radiation) factors, skeletal muscle index (SMI), and body mass index (BMI) residuals. We assessed effect modification via product terms of adiposity with age (>=/<55 years), sarcopenia (SMI>=/<40 cm2/m2) and chemotherapy (yes/no). RESULTS: At diagnosis, mean (SD) age was 55 (11) years and BMI was 28 (6) kg/m2. Over a maximum follow-up of 11 years, 669 CVD events occurred. Independent of BMI and other covariates, women in the highest (v. lowest) tertile of total adiposity had a higher risk of CVD, heart failure, stroke and CAD; HRs (95%CI) were 1.45 (1.15–1.81), 1.78 (1.24–2.57), 1.89 (1.25–2.87), and 1.52 (0.83–2.79), respectively. Results were similar for visceral adiposity, and by age and sarcopenia, but were stronger for women receiving chemotherapy: e.g., the HR (95%CI) for the highest (v. lowest) tertile of total adiposity with CVD risk was 1.76 (1.33–2.33) for women who received chemotherapy versus 0.93 (0.63–1.38) for women who did not, p- interaction = 0.04. CONCLUSIONS: Women who enter a breast cancer diagnosis with greater total and visceral adiposity are at higher risk of subsequent CVD, particularly if they receive chemotherapy. Our results suggest that body composition - independent of BMI and other factors - can identify patients with high CVD risk for additional monitoring, tailored treatment plans and targeting of preventive interventions.