IGF1 and obesity due to melanocortin 4 receptor deficiency: Results: By analyzing the available literature data, this study determined that hyperinsulinemia (IGF-1 pathway), hyperglycemia, and obesity (>102 cm in men and >88 cm in women) are highly associated with the development of esophageal cancer (primarily with Barret’s long and short segment as precancerosis), gastric cancer (through reactive oxygen species), and both pancreatic (1.5–2.4 higher risk) and colorectal cancer (30% higher risk).