Patterns of gastric cancer metastasis in the United States

Background: Literature on the epidemiology of gastric cancer metastasis is limited, although outcomes are known to be poor. We describe patterns of gastric cancer metastasis and treatment in the United States. Methods: Patients with metastatic gastric adenocarcinoma were identified in the NCDB from 2004 to 2016. We describe univariate associations between sites of metastasis and clinicopathologic characteristics and treatment modalities, using chi-square and Kruskal-Wallis tests. Overall survival was calculated using Kaplan-Meier estimation. Results: 43% (n = 2028) of patients presented with peritoneal metastases, 26% (n = 1228) with liver metastases, 20% (n = 941) with distant nodes, and 11% (n = 552) with bone, brain or lung metastases. Compared to liver metastases, peritoneal metastases were more likely from an antral primary site (28% v. 16%); associated with signet ring histology (34% v. 6%); tumor grade of III/IV (85% vs. 60%) (p < 0.0001 for all). Isolated metastasis to distant lymph nodes had the longest median overall survival (7.6 months, p < 0.0001). Conclusions: Most patients with metastatic gastric cancer in the USA present with peritoneal disease. Predictors for peritoneal metastases include primary antral site, signet ring histology and higher tumor grades.