OBJECTIVETo study subtype classification of gastric neuroendocrine neoplasm (NEN) and their clinicopathological characteristics in order to provide reference for clinical practice.

METHODSClinicopathological data of 241 gastric NEN patients (174 cases from China-Japan Friendship Hospital and 67 cases from The First Affiliated Hospital of Sun Yat-Sen University) between January 2011 and June 2016 were retrospectively summarized. According to serum gastrin, 24-hour intragastric pH monitoring and pathological grade, patients with gastric NEN were divided into 4 types: type I( (hypergastrinemia and achlorhydria, related to autoimmune chronic atrophic gastritis), type II( [hypergastrinemia and Zollinger-Ellison syndrome, related to gastrinoma or multiple endocrine neoplasia type I( (MEN-I()], type III( (sporadic disease with normal serum gastrin level), and type IIII( [poorly differentiated gastric neuroendocrine carcinoma (NEC) and mixed adenoneuroendocrine carcinoma (MANEC)]. Clinicopathological features, treatment and prognosis of 4 types were analyzed.

RESULTSOf 241 gastric NEN cases, there were 86 cases (35.7%) in type I(, 7 cases (2.9%) in type II(, 61 cases (25.3%) in type III( and 87 cases(36.1%) in type IIII(. Among 86 cases of type I( gastric NEN, 73 cases (84.9%) were multiple lesions,tumor size of 66 cases (76.7%) was less than 1 cm, all the 86 cases were polypoid or granular lesions. 2 cases(2.3%)presented distant metastasis, 69 cases (80.2%) had pathological grading as NET G1; most of them received endoscopic surgery treatment and follow-up; somatostatin analogs(SSA) was used in patients with multiple lesions and repeated recurrence after endoscopic treatment. Among 7 cases of type II(, 4 cases were gastrinoma, 3 cases MEN-I(; 5 cases presented distant metastasis; treatment included surgery, SSA and proton pump inhibitor (PPI) therapy. Among 61 cases of type III( gastric NEN, 49 cases(80.3%) were single lesion,tumor size of 25 cases(41.0%) was more than 2 cm, 29 cases(47.5%) had lymph node metastasis or distant metastasis; treatment included endoscopic resection, surgery or SSA therapy according to the tumor staging. Among 87 patients of type IIII( gastric NEN, 74 cases(85.0%) had single lesion,tumor size of 51 cases (58.6%) was more than 2 cm; lesions were found in gastric cardia in 35 cases (40.2%); 65 cases (74.7%) had lymph node metastasis or distant metastasis; treatment included chemotherapy, or surgery plus chemotherapy. At the end of follow-up(June 30, 2016), 58 patients were dead, including 1 case of type I(, 12 cases of type III( and 45 cases of type IIII(. The overall survival rate of all the patients was 74.2%, and was 98.8%, 100%, 79.3%, 39.2% of types I(, II(, III(, IIII( respectively. The overall survival rate between type III( and type IIII( gastric NEN was significantly different(P = 0.000).

CONCLUSIONSSubtype classification of gastric NEN is very significant for making therapeutic decisions and prognostic evaluation. Patients of type I( or type II( gastric NEN have good prognosis,while those of type III( and type IIII( have poor prognosis, and those of type IIII( have the worst prognosis.