Clinicopathological Features Of Multifocal Gastric Carcinoma: A Retrospective Study

453 Background: The occurrence of multifocal gastric carcinoma (MGC) is growing in China, while relevant study remains limited. This study aimed to collect more information of MGC for further research. Methods: Patients with MGC treated at China National Cancer Center from January 2010 to December 2017 were enrolled in this retrospective study. A 6-month interval was used to separate synchronous and metachronous foci. Results: 103 patients were included. 88 (85.4%) were males. 96 (93.2%) patients had two foci and 7 (6.8%) had three or more foci, contributing a total of 216 tumor foci. 185 (85.6%) foci were adenocarcinoma, 18 (8.3%) were intraepithelial neoplasia, 2 (0.9%) were lymphoepithelioma-like carcinoma and 1 (0.5%) was small cell carcinoma. Intestinal, diffuse, and mixed type accounted for 49.7%, 14.6% and 11.4% respectively, with 24.3% unknown.In 96 patients with 2 foci, 56 (58.3%) patients had synchronous diseases, and 40 (41.7%) had metachronous diseases. The median age at the diagnosis of first tumor was 62 (55-71) years. The median diagnosis interval of metachronous tumor foci was 41.4 (23.5-88.3) months. The locations and sizes of foci are shown in Table. In synchronous cases, 6 foci of accessory tumor were less than 1cm including one being 0.4 cm. In metachronous cases, 4 foci of second tumor were less than 1 cm. 51 (49.5%) patients were current smokers or ex-smokers, and 44 (42.7%) were regular alcohol consumers. 26 (25.2%) patients had a first-relative family history, including 14 (13.6%) having a family history of gastrointestinal carcinoma. Conclusions: The second gastric tumor should be thoroughly detected to avoid missed diagnosis, since the accessory tumor might be rather small. Further genetic research is warranted to explore the potential pathogenesis of MGC. [Table: see text]