The development of the metabolic syndrome and insulin resistance after adjuvant treatment for breast cancer

BACKGROUND:: Adjuvant breast cancer treatment is associated with a number of adverse physical changes, including weight gain, and therefore may represent a critical period for the development of metabolic disturbance. OBJECTIVE:: The aim of this study was to evaluate changes in the presentation of the metabolic syndrome (MetSyn) and insulin resistance from breast cancer surgery to postcompletion of adjuvant treatment. METHODS:: Sixty-one participants who had completed metabolic screening, including fasting blood samples and anthropometric measurements, on the morning of breast cancer surgery were recruited. Measures were repeated after completion of adjuvant treatment. Change in the proportion of participants presenting with the MetSyn was evaluated using the related-samples McNemar test, and changes in measures of glucose metabolism (fasting insulin, insulin resistance [homeostatic model assessment index], and glycosylated hemoglobin [HbA1c]) were analyzed using paired t tests. The Kruskal-Wallis test was used to compare differences in changes in metabolic parameters across clinical and lifestyle characteristics. RESULTS:: There was a significant (P < .001) increase in fasting insulin (mean [SE] change, 2.73 [0.57] mU/L), homeostatic model assessment index (0.58 [0.14]), and HbA1c level (4.49 [5.63] mmol/mol) from baseline to follow-up along with an increase in the proportion diagnosed with the MetSyn (P = .03). Those with the MetSyn at diagnosis experienced a greater increase in insulin resistance. Premenopausal women experienced greatest increases in HbA1c level. CONCLUSIONS:: Results demonstrate the development of significant metabolic dysfunction, characterized by glucose dysmetabolism and MetSyn, after adjuvant treatment for breast cancer. IMPLICATIONS FOR PRACTICE:: Interventions to improve the metabolic profile of breast cancer survivors are warranted. © 2014 Wolters Kluwer Health Lippincott Williams & Wilkins.