Aims Almost half of deaths among women diagnosed with breast cancer are attributable to non-breast cancer causes, most commonly cardiovascular disease. Metabolic syndrome (MetS) is a cluster of risk factors that increases risk of cardiovascular disease, but is also independently associated with poor outcomes (disease recurrence and death) in breast cancer survivors. We aimed to evaluate the effects of a telephone-delivered weight loss intervention (diet and exercise) on MetS in breast cancer survivors.
Methods Eligible women (18-75 years, BMI 25-45kg/m2, stage I-III breast cancer, <2-years post-treatment completion) were allocated to intervention (n=79) or usual care (n=80). The intervention group received 22 counseling calls, with optional text messages, over 12 months. MetS components (waist circumference, triglycerides, HDL-cholesterol, glucose and blood pressure) were measured at baseline, 6- , 12- and 18 months; and were used to compute a MetS risk score (average of z-scores [(value – population mean) / sample SD] for MetS components). Intervention effects, assessed by linear mixed models, accounted for repeated measures and baseline values.
Results At baseline, participants were (mean±SD) aged 55±9 years, with a BMI of 31.4±5.0 kg/m2, 10.7±5.0 months post-diagnosis, and 47% had MetS. At 12 months, significant intervention effects were observed in MetS risk score, waist circumference and fasting glucose, which were sustained at 18 months for MetS risk score and waist circumference. Significant intervention effects were observed for blood pressure at 6 months only, and no significant intervention effects were observed for lipids.
Conclusions Sustained improvements in MetS risk score and waist circumference were achieved following a pragmatic weight loss intervention; but limited improvements were observed for other MetS components. Further research is needed to understand how to improve MetS components more comprehensively using interventions that may be translatable into real-world practice, in order to improve breast cancer outcomes and reduce chronic disease risk.