Multiple primary cancers in patients with gastric cancer: A retrospective study in China National Cancer Center.

Abstract

337 Background: Gastric cancer (GC) is common in China. With the total incidence of cancer keeping rising in China, the occurrence of multiple primary cancers with GC is growing. Early detection and diagnosis of second or more primary cancers are vital for patients’ survival. Methods: Patients with multiple primary cancers containing gastric adenocarcinoma treated in China National Cancer Center from January 2010 to December 2017 were included. A 6-month interval was used to separate synchronous and metachronous cancers (according to IARC/IACR criteria). Results: 479 patients met the criteria were included, with 452 (94.4%), 24 (5.0%), 3 (0.6%) patients having two, three or more primary cancer sites respectively, contributing a total of 510 cancer sites besides stomach (Table). Malignancies at 257 (50.4%) sites occurred with GC synchronously, while 253 (49.6%) occurred metachronously. The median age at the diagnosis of first cancer was 59 (interquartile range [IQR], 53-66) years. The median interval between the diagnosis of first primary cancer and metachronous second one was 50.3 (IQR, 23.7-97.0) months. Cancers outside gastrointestinal (GI) tract were more likely to occur with GC metachronously, while GI tract cancers were more likely to occur synchronously (χ²=55.36, p<0.001). Out of 479 patients, there were 352 (73.6%) male and 127 (26.4%) female. The most common associated cancer was esophagus cancer (142, 40.3%) in male, and breast cancer (31, 25.4%) in female. 236 (49.8%) patients were current smokers or ex-smokers, and 190 (40.1%) were regular alcohol consumers. 110 (23.2%) had first-degree relative cancer family history, with 84 (17.7%) having GI tract cancer family history. Conclusions: GI tract including esophagus and colorectum should be carefully scrutinized during GC peri-operation period. Further genetic research is warranted to explore the potential pathogenesis of multiple primary cancers.[Table: see text]