The relationship of insulin resistance and metabolic syndrome with known breast cancer prognostic factors in postmenopausal breast cancer patients.

PURPOSE The aim of this study was to investigate the effect of metabolic syndrome and insulin resistance at the time of diagnosis on the known prognostic factors of breast cancer in postmenopausal breast cancer patients. METHODS The study included 71 patients with a recent diagnosis of postmenopausal breast cancer, admitted at the Medical Oncology outpatient clinic of the Izmir Ataturk Training and Research Hospital between June 2010 and June 2011. We determined whether the patients had metabolic syndrome and insulin resistance at diagnosis, and recorded known prognostic factors, such as tumor size, axillary lymph node involvement, presence of distant metastasis, tumor grade, estrogen receptor (ER), progesterone receptor (PR), and CerbB-2 status. RESULTS Among 71 patients, 25 (35%) had metabolic syndrome at the time of diagnosis, and 33 (46%) had insulin resistance with Homeostasis Model of Assessment-Insulin Resistance (HOMA-IR)>2.7. No statistically significant difference was found in the prognostic values of breast cancer, i.e. tumor size, axillary lymph node involvement, distant metastasis, tumor grade, ER, PR, and CerbB-2 status between the patients with and without metabolic syndrome. There was no statistically significant difference in the prognostic factors of breast cancer at the time of diagnosis between 33 patients with insulin resistance and 38 patients without insulin resistance. CONCLUSION Several previous studies showed a negative relationship between metabolic syndrome and insulin resistance and prognostic factors of breast cancer in postmenopausal breast cancer patients. However, our study failed to show such a relationship. The relationship between metabolic syndrome and insulin resistance and postmenopausal breast cancer was not well demonstrated due to the small number of patients, unknown duration of the metabolic syndrome and insulin resistance, and shorter follow-up period. Further studies are required to demonstrate the effect of metabolic syndrome and insulin resistance on the prognosis of breast cancer, including larger number of patients and longer follow-up periods.