Key Word(s): 1. duodenum; 2. EMR; 3. nonampullary Presenting Author: SHINYA KONDO Additional Authors: TAKAYOSHI FUJITA, YOSHIE TSUZUKI, YU SOBAJIMA, TAKAFUMI ANDO, HIDEMI GOTO, MASATOSHI SAKAKIBARA Corresponding Author: SHINYA KONDO Affiliations: Aichi Cancer Center Aichi Hospital, Aichi Cancer Center Aichi Hospital, Aichi Cancer Center Aichi Hospital, Nagoya University Graduate School of Medicine, Nagoya University Graduate School of Medicine, Aichi Cancer Center Aichi Hospital Objective: With the progress of endoscopic diagnosis and treatment, endoscopic treatment has come to be used for gastric adenomas

and early gastric cancers (EGCs). Endoscopic submucosal dissection (ESD) has become accepted as a minimally invasive treatment for superficial gastric neoplasms. However, the development of metachronous gastric neoplasms has been occasionally

detected during follow-up after ESD. The clinicopathologic characteristics of these Metformin concentration lesions occurring after ESD were investigated. Methods: From August 2006 to May 2014, stomach ESD was performed for 302 patients with 351 lesions of gastric adenoma and differentiated-type EGC at Aichi Cancer Napabucasin Center Aichi Hospital. Periodic upper gastrointestinal endoscopy, blood tests, and chest and abdominal computed tomography were performed every 6 to 12 months after treatment. During the follow-up period, 24 metachronous lesions (21 patients) were discovered at endoscopy more than 1 year after initial ESD. The characteristics of these lesions were examined retrospectively. Results: The median age at initial ESD was 72 (range, 56–82) years. The male to female ratio was 18:3. On endoscopy, all patients were found to have atrophic gastritis of the open-type according to the Kimura-Takemoto classification. Helicobacter pylori testing was positive in 15 patients

(71.4%), negative in 5 patients (23.8%), and unknown in 1 patient (4.8%). Of these 15 H. pylori- positive patients, 14 underwent H. pylori eradication therapy after initial ESD, and it was successful in 13 (92.9%). The median duration from initial ESD to the detection of a metachronous lesion was 31.6 (range, 12.8–83.8) months. The locations of the lesions were classified as follows: upper third (U), middle third (M), and lower third (L). Of 22 primary lesions, 1 lesion (4.5%) was U, 9 lesions (41%) were M, and 12 lesions (54.5%) were medchemexpress L. The gross type was 0-I in one lesion (4.5%), 0-IIa in 11 lesions (50%), and 0-IIc in 10 lesions (45.5%). The median tumor size was 13 (range, 2–50) mm. En bloc resection was performed for 21 lesions (95.5%). There were no complications. On pathological examination, 16 were tubular adenocarcinoma, and 6 were tubular adenoma. Histologically, curative resection was obtained in 20 lesions (90.9%). In contrast, the location of 24 metachronous lesions was U in 8 lesions (33.3%), M in 5 lesions (20.8%), and L in 11 lesions (45.8%). The gross type was 0-IIa in 13 lesions (54.