ESR1 and breast cancer: This study aimed to investigate the relationships between serum levels of insulin-like growth factor binding protein 3 (IGFBP-3), insulin-like growth factor 1 (IGF-1), the IGFBP-3 A-202C polymorphism and hormone receptor subtypes: estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) with respect to breast cancer risk in Palestinian women.