Abstract: Objective To study the risk factors of lymph node metastasis in patients with multifocalgastric cancer and to analyze its influence on the prognosis.
Methods From January 2013 to January 2017，2012 patients were diagnosed by pathology and underwent surgery，36 patients with multifocal gastric cancer were enrolled into this study.The retrospective analysis was performed.The clinic-pathological data were retrospectively analyzed，mainly including age，gender，surgical mode，carcinoma-related date（quantity，location，degree of differentiation，T stage，tumor diameter ，vascular tumor thrombus， nerve tumor thrombus） and lymph node status（number of lymph nodes dissected，lymph node metastasis）.36 patients were divided into non-metastatic group（17 cases）and metastatic group（19 cases）.Logistic regression were performed to analyze the risk factors of lymph node metastasis.The 3-year overall survival rate of the two groups was calculated.The survival analysis was performed using the Kaplan-Meier and log-rank test and multi-factor analysis with the Cox proportional hazard regression model.
Results Univariate analysis showed that the depth of invasion，nerve invasion and lesions distributed in different areas were the risk factors of lymph node metastasis（P<0.05）.Multivariate regression analysis showed that depth of main tumor invasionis independent risk factors for lymph node metastasis（P<0.05）.The 3-year survival rate of lymph node metastasis group was 52.6%.The 3-year survival rate of lymph node non-metastatic group was 88.2%.The results of follow-up showed that the 3-year survival rate of the patients with lymph node metastasis was significantly lower than that of the patients without metastasis，with significant difference（P<0.05）.
Conclusion Multifocal gastric cancer is a special type of gastric cancer，depth of main tumor invasionis independent risk factors for lymph node metastasis.Patients with lymph node metastasis have a poor prognosis.

Key words: stomach neoplasms, multiple primary cancers； lymph node metastasis, risk factors, prognosis