Duodenal Adenoma

To learn how well nitrous oxide cryoballoon ablation, a procedure that uses extreme cold to destroy abnormal tissue, works in treating flat duodenal adenomas (abnormal growths in the small intestine) in people with FAP or Lynch syndrome (HNPCC).

Mucosal and submucosal lesions of the duodenum represent a diverse group of pathologies, ranging from benign adenomas to lesions with significant malignant potential. Endoscopic resection has emerged as a minimally invasive approach; however, the success rates, recurrence patterns, and long-term outcomes remain poorly defined due to the heterogeneity of these lesions. This study aims to retrospectively evaluate the endoscopic management and long-term outcomes of patients who underwent endoscopic resection of mucosal and submucosal lesions in the duodenum and ampulla over a 15-year period. The investigators aim to assess key procedural outcomes, including complete resection rates, recurrence, complication rates, recurrence and morbidity and mortality of duodenal or ampullary malignancy. By analysing these factors, the investigators hope to better understand the role of endoscopic therapy in managing these challenging lesions and identify predictors of long-term success. This data will help guide future practice and optimize surveillance strategies for patients undergoing endoscopic resection in this complex anatomical region. Primary Objective 1. To evaluate the effectiveness of endoscopic resection of mucosal and submucosal lesions (MSML) in the duodenum and ampulla. 2. To assess the safety profile of the procedure. 3. To investigate long-term outcomes, including rates of recurrence, residual disease, and malignancy. Secondary Objectives 1. Diagnostic yield of endoscopic surveillance post endoscopic resection 2. Requirements for surgery

Duodenal cancer is the leading cause of cancer-related mortality in patients with familial adenomatous polyposis (FAP), yet the current Spigelman staging system provides limited predictive accuracy for advanced neoplasia. The DRACO study (Duodenal Risk Assessment in adenomatous polyposis Coli -Oncogene) is a multicenter, STROBE- and CONSORT-compliant cohort study that analyzes upper endoscopies from genetically confirmed FAP patients across independent cohorts to develop, validate, and externally test two multivariable risk models.