IGF1 and colonic neoplasm: Furthermore, AACE guidelines suggest that follow-up colonoscopy be performed at time intervals “appropriate for patients at higher-than-average risk for colon cancer” [13], whereas the Endocrine Society guidelines suggest screening every 5 years for patients with elevated IGF-1 levels or polyps and every 10 years for patients with normalized IGF-1 levels and no polyps [14].