Exercise, metabolic syndrome, and cardiovascular fitness in breast cancer survivors.

Abstract

165 Background: Metabolic syndrome (MetS) has been reported higher in breast cancer survivors (BCS) compared to age-matched postmenopausal women. The risk for cardiovascular disease and diabetes is significantly increased in women with MetS. Lifestyle behaviors are recommended first line interventions to reduce risk for MetS. Methods: From a 12 month randomized controlled trial (RCT) of a fitness center exercise intervention compared to a home physical activity group, the criteria for MetS (3 of 5 components: waist circumference [WC] ≥ 80cm, triglycerides ≥ 150mg/dL, HDL cholesterol < 40 mg/dL, blood pressure [BP] ≥ 130/85 mmHg, fasting blood sugar [FBS] > 100mg/dL) were used to identify BCS with MetS. General estimating equation was employed for longitudinal changes. Heart rate recovery (reduction in heart rate from peak heart rate at one minute after exercise stress test) was used as a measure of cardiovascular fitness. Pearson correlation coefficients assessed associations between heart rate recovery and metabolic outcomes. Results: Of 148 subjects in the RCT, 21.6% (N = 32) met the criteria for MetS, with a higher baseline incidence in the home (30.1%) versus fitness center (13.3%) groups (p = 0.01). Of subjects on Tamoxifen, 30.9% had MetS, compared to 17.1% on an aromatase inhibitor and 20.7% not on endocrine therapy; these were not significantly different (p = .28). Among those with MetS at baseline, we observed a significant decrease in MetS (p < .01) with significant changes in HDL (p = 0.02) and FBS (p = .01) after the 12 month intervention. The fitness center and home physical activity groups both resulted in fewer subjects meeting MetS criteria at 12 months, but only the home group had a significant change over time (OR = 0.66 (0.44, 0.98) p = .04). Heart recovery rate at 6 months was significantly associated with all 5 MetS components: WC (-0.28 p < .01), triglycerides (-0.32 p < .01), HDL (0.20 p = .04), systolic BP (-0.38 p < .01), diastolic BP (-0.27 p < .01) and FBS (-0.35 p < .01). Conclusions: All-cause mortality now exceeds breast cancer specific mortality. MetS identifies a unique vulnerable population of BCS at high risk for cardiovascular disease. Lifestyle behaviors represent critical risk reduction strategies.