The patients where selected after duodenoscopy, biopsies and endoscopic ultrasound (EUS). Adenoma with at least low grade dysplasia (LGD) was required for inclusion. Two other criteria were needed in asymptomatic patients with LGD : - an ampullary size \> 1 cm at endoscopy in case of FAP ; - two series of positive biopsies in case of sporadic tumors. EUS staging was estimated as follows : uT1 = tumor without invasion of the muscularis propria (MP) of the duodenum; uT2 = invasion of the MP without invasion of the pancreas ; uT3 = invasion of pancreas ; uN- = no suspicious lymph nodes ; uN+ suspicious lymph nodes. Finally, intraductal pancreatic and/or common bile duct (CBD) growths were estimated. Only uT1N- tumors without intraductal growth were included. Exclusion criteria were: - previously treated ampulloma; - metastatic disease at CT-scan; - advanced tumor at duodenoscopy (ulceration or induration involving the duodenal roof of the papilla) ; - advanced tumor (\> uT1 and/or N+) and/or intraductal invasion at EUS - absence of adenoma on the resected specimen. Intraductal ultrasonography (IDUS) was optional. IDUS staging was considered as follows : uTm = tumor without invasion of the duodenal submucosae; uTsm = tumor with invasion of the duodenal submucosae.

Investigators were 11 experienced endoscopists (10 centers) specialized in pancreaticobiliary diseases and selected as follows: at least 4 years of endoscopic retrograde cholangiopancreatography (ERCP) practice with at least six EP in the last 3 years. The procedure was standardized: submucosal injection of saline solution was reserved to duodenal extension around the ampulla; a standard polypectomy snare was used with endocut current; resection has to be performed in one fragment, the piece-meal technique was only accepted for lesions larger than 2 cm. The size of the lesion was estimated by comparison with the opened snare. The ampullary tumor was snared at the base and constant tension was applied to the snare loop during electrocautery until the lesion was sectioned. The endoscopist had to mention if the procedure was considered complete or not. When needed, hemostasis was performed by injection of diluted adrenalin (1:10 000) and/or hemoclips. Realization of any additional procedures (stone removal, biliary or pancreatic sphincterotomy, biliary or pancreatic stent placement...) were left to the endoscopist decision and recorded. Patients were hospitalized for at least 2 days after the procedure. During the first 24 hours, fasting and proton pomp inhibitor (PPI) (+/- antibiotics) administration were recommended. Feeding was accepted on day 2 in the absence of complications and final discharge at day 3. Complications occurring after discharge were recorded when reported by other health care provider or by the patient at the subsequent FU session. We documented the complications and graded their severity according to the Consensus Criteria. Treatment of the complications was recorded. Finally, the length of hospital stay and the morbidity rate were calculated.

Size, number of fragments, and final staging were stated. In case of duodenal submucosal invasion a complementary surgery was discussed. In case of absence of tumor on the resected specimen, an experienced pathologist (JYS) performed a second reading of initial biopsies.

A first endoscopic control was performed after 4 to 8 weeks with retrieval of the eventual stents and systematic biopsies. In case of evident persistence of tumoral tissue a complementary resection was done, if possible, with a new endoscopic control 4 weeks later. Follow-up (F-U) was performed at 6, 12, 18, 24 and 36 months, including clinical examination, duodenoscopy with biopsies and EUS +/- ERCP. Therapeutic success was concluded in case of: 1) R0 resection = absence of invasion of duodenal submucosa on the resected specimen and complete excision of the lesion (no residual tumoral tissue at the first endoscopic control with biopsies, or at the second control in case of iterative resection) 2) no recurrence during long-term F-U. Therapeutic failure was defined as: - early failure in case of duodenal submucosal invasion on the resected specimen and/or positive biopsies without possibility of complementary resection at first control (or second control in case of iterative resection); - late failure in case of positive biopsies (persistence or recurrence) during the FU.