Multicentric Study About Pathological Risk Factors for Lymph Node Metastasis in Malignant Colorectal Polyps

Colorectal cancer screening showed an increased incidence of malignant colorectal polyps pT1 after endoscopic excision. Their management is not yet standardized, for the presence of histological features increasing early lymph node involvement. The literature has proposed several histopathological criteria, for which the risk of lymph node metastasis can vary (6-20%), but final data are not yet available. Aim 1.To collect data about patients undergoing an endoscopic polypectomy with histologic finding of pT1, retrospectively and prospectively, dividing both databases into two groups, endoscopic group (EG) and surgical group (SG) Aim 2. To analyze retrospectively which pathological criteria can increase the risk of lymph node metastasis and to elaborate a prognostic score for lymph node metastatic risk Aim 3. To verify prospectively the prognostic score capacity on predicting lymph node metastasis Aim 4. To calculate the disease free survival, overall survival, local recurrence rate and distal recurrence rate and verify if there is a difference between EG and SG According to literature, the most important histopathological criteria to establish the high risk of lymph node metastasis are: 1. Lateral margin of healthy tissue (high risk: \1000 μM or sm2-sm3 for sessile polyps; Haggitt level 4 for pedunculated polyps) 3. Vascular invasion (high risk: presence) 4. Lymphatic invasion (high risk: presence) 5. Tumor budding (high risk: presence) 6. Tumor differentiation (high risk: grade G3-G4 or mucinous) A database will be used by all participating centres for collecting clinical and pathological data. All the analyses will be centralized by the PI. Uni-multivariate analyses will be conducted at the end of data collection for retrospective arm and at 2 years of follow-up for prospective arm. Impact: This study aimed to investigate pathological risk factors for lymph node metastasis in pT1 col