Colorectal cancer screening programs result in an early diagnosis of the disease. In 2007, 250 malignant polyps were identified in Lombardy, out of 1,329 screen-detected colorectal carcinomas. The Italian Group for Colorectal Cancer (GISCoR) promoted the multicentric study "Endoscopic Follow-up versus Surgical Radicalization of Malignant Polyps after Complete Endoscopic Polypectomy" (SEC-GISCoR). The protocol was a multicentric, prospective, observational, non-randomized study. It included patients diagnosed a colorectal malignant adenoma, after complete endoscopic removal. From November 2005 to September 2009, three participating centers enrolled 120 patients with malignant polyps after "complete" endoscopic polypectomy; malignant polyps were classified as "low risk" or "high risk". The study had two arms: "Intensive follow-up" (42 patients: 32 with low-risk and 10 with high-risk polyps) and "Surgical radicalization" (78 patients: 5 with low-risk and 73 with high-risk polyps). Data were collected using an online CRF. Overall, 37/120 polyps (30.8%) were low risk and 83/120 (69.2%) were high risk. 42 out of 120 patients (35%) were enrolled in the "clinical follow-up" arm, while 78/120 (65%) entered the surgery arm. In 15 cases, patients were not enrolled in the correct arm, according to the criteria agreed upon before starting the study. There still is a high incidence (11.5%) of pathological mismatches. No clinical event was reported in 2.9 years of follow-up. In conclusion, some differences emerged in the management of patients with malignant polyps among participating centers (p < 0.001), mismatches can be explained by high surgical risk or patient's choice. Only in 5 cases (4.2%), did data analysis not allow to exactly determine the reason for a choice different from protocol criteria. The availability of new risk factors and the evidence of pathological mismatches confirmed the need for future studies on this issue.