LEP and obesity due to melanocortin 4 receptor deficiency: In breast cancer, obesity-related host factors, such as components of the secretome (e.g., insulin, IGF-1, leptin, adiponectin, steroid hormones, cytokines, vascular regulators, and inflammation-related molecules), explain the causative link between increased risk of breast cancer in postmenopausal women and poor prognosis in pre- and postmenopausal women (161).