IGF1 and hyperinsulinism: Epidemiological evidence shows that metabolic syndrome (MetS), fasting hyperinsulinemia, and high levels of circulating insulin-like growth factor-1 (IGF-1) are risk factors for the development and recurrence of breast cancer (BC) (Andò et al. 2019; Calori et al. 2011; Duggan et al. 2011; Endogenous Hormones and Breast Cancer Collaborative Group et al. 2010; Goodwin et al. 2002; Pasanisi et al. 2008).