The Effect of Exercise Training on Serum Glucose and Lipid Profiles in Patients With Breast Cancer: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Background: Despite several studies on the effects of exercise training on glucose and lipid profiles in patients with breast cancer, no earlier study has systematically summarized their findings. Current systematic review and meta-analysis have been done on earlier clinical trials in this topic. Methods: Relevant studies published up to May 2020 were searched through PubMed, SCOPUS, and Google Scholar using predefined keywords. Studies that examined the effect of exercise training on serum glucose and lipid profiles in adult women with breast cancer were included. Results: A total of 16 studies were included. Combining 10 effect sizes, exercise training had no significant influence on serum fasting plasma glucose concentrations (weighted mean difference [WMD] = 4.87; 95% confidence interval [CI], -4.65 to 14.29). However, it resulted in significant reduction of serum insulin (WMD= -2.37; 95% CI, -3.57 to -1.16) and homeostatic model assessment for insulin resistance (WMD = -0.71; 95% CI, -1.27 to -0.15) in 14 and 8 studies, respectively. Pooling 6 effect sizes, exercise training did not change serum total cholesterol (WMD = -11.99; 95% CI, -32.42 to 8.45), low-density lipoprotein (WMD = -3.21; 95% CI, -10.45 to 4.04), highdensity lipoprotein (WMD = 4.13; 95% CI, -6.20 to 14.46), and triglyceride (WMD = -23.34; 95% CI, -66.96 to 20.29) concentrations. Subgroup analyses showed beneficial effects of exercise training on outcomes of interest among studies with higher methodological quality. Conclusion: Current meta-analysis demonstrated significant reductions in serum levels of insulin and insulin resistance following exercise training. However, exercise training had no significant effect on serum levels of fasting plasma glucose, total cholesterol, triglyceride, high-density lipoprotein, and low-density lipoprotein. Further high-quality studies are needed to shed light on this issue.