Epidemiological data suggest a close link between obesity and breast cancer, the most frequently occurring cancer in women. The metabolic syndrome is typically associated with abdominal obesity and comprises disturbances in glucose and/or lipid metabolism and/or hypertension. Recent studies have established a specific association between the metabolic syndrome - as well as its components - and breast cancer, indicating both an increased risk of developing breast cancer and a poorer prognosis. In premenopausal women, obesity might have a protective effect only on receptor-positive tumors, whereas a positive association was observed between obesity/abdominal obesity and an increased risk of triple-negative breast cancer (TNBC). Overall survival and disease-free survival were reported to be significantly shorter in premenopausal obese women with TNBC compared to non-obese women, but these results are still inconsistent and need further research. The metabolic syndrome is characterized by a state of insulin resistance/hyperinsulinemia and subacute chronic inflammation, with both conditions offering a plausible mechanistic link towards breast cancer. Thus, in addition to their increased risk of cardiovascular morbidity and mortality, women with this syndrome represent a group at elevated risk of developing breast cancer and with poorer prognosis.
Keywords: Abdominal obesity; Breast cancer; Metabolic syndrome; Triple-negative breast cancer (TNBC).