Higher insulin resistance & adiposity in post-menopausal women with breast cancer treated with aromatase inhibitors

Context: Aromatase deficiency causes obesity and insulin resistance in aromatase knockout mice and humans with rare mutations of the aromatase gene (CYP19). Aromatase inhibitors are a commonly prescribed therapy in post-menopausal breast cancer. Objective: We hypothesized that aromatase inhibitors induce obesity and insulin resistance when used in treatment of breast cancer. Design: Case-control study Setting: University teaching hospital Participants: 20 post-menopausal breast cancer patients, treated with aromatase inhibitor and 20 age-matched controls. Main outcome measures: Primary outcome measure was insulin sensitivity index – Matsuda, derived from a 75g oral glucose tolerance test. Body composition was assessed by DEXA and subcutaneous adipose tissue biopsies obtained for assessment of mRNA transcript levels. Data are mean ± SEM (inhibitor vs controls). Results: Aromatase inhibitor therapy was associated with significantly lower insulin sensitivity (5.15 ± 0.4...