Early Breast Cancer Agressiveness does not Differ Between Insulin-Sensitive and Insulin-Resistant Postmenopausal Non-Diabetic Women

ABSTRACT Background The metabolic syndrome is known to negatively influence breast cancer outcome. One of the syndromes components is hyperinsulinism, which can exert tumor-promoting effects directly or through increased hepatic IGF1-production. A fasting insulin concentration > 10 µIU/ml and/or a HOMA score > 2.6 are considered diagnostic for the metabolic syndrome. We performed a pilot study to evaluate the relation between insulin resistance and tumor characteristics. Study design Prior to surgery we collected blood samples of 33 consecutive non-diabetic postmenopausal women with early breast cancer to measure fasting insulin and glucose concentration. Correlation analyses were performed for both fasting insulin and HOMA-score (insulin resistance index) and parameters tested were body mass index, mitotic activity index (MAI), Bloom Richardson score (BNR) and tumor diameter. We also compared nodal status, ER-status and Her2-status of insulin-resistant and insulin-sensitive breast cancer patients. Results Median age was 66 (49- 86) years and median BMI was 25.8 (18.6- 45.4) kg/m2. Median MAI was 7 (1-52), median tumor diameter was 12 (3- 70) mm and 9 patients had node-positive disease ( 2 N0itc, 5 N1, 2 N2). Insulin resistance was found in 5 (15 %) patients. BMI showed a strong positive correlation with insulin concentration and HOMA score (2-sided Pearson test; P= 0.000). Insulin resistant and insulin sensitive patients however did not differ in terms of MAI, BNR, tumor diameter, nodal status, ER-status and Her2-status. Conclusion In postmenopausal non-diabetic women with early breast cancer insulin resistance is encountered quite often. It does however not appear to alter cancer biology. Disclosure All authors have declared no conflicts of interest.