INSR and breast cancer: Increased circulating insulin levels and the overexpression of IGFs are often consequences of obesity.30,48 Excess visceral adipose tissue (VAT) leads to insulin resistance and hyperinsulinaemia.43 Hyperinsulinemia is correlated with an increased risk of developing BC and poor prognosis in obese BC patients.28 Insulin binds to insulin receptors (IRs) expressed on the surface of tumor cells.