Combination Of Lymphovascular Invasion And The TNM Staging System Improves Prediction Of Prognosis In N0 Stage Gastric Cancer

Background TNM staging system is a widely used system for evaluating prognosis of solid tumors including gastric cancer.The prognosis of Lymph node-negative(N0)stage patients may not be evaluated accurately only by T-stage.In addition,the guidelines for the treatment of gastric cancer in East and West still do not agree on whether patients with p T3N0M0 should receive postoperative adjuvant chemotherapy.Objective This study sought to explore whether lymphovascular invasion can affect the prognosis of patients with stage N0 gastric cancer and to establish a modified TNM staging system,also,to evaluate the survival benefit of adjuvant chemotherapy for such patients.Method From January 2006 to December 2011,a total of 2102 gastric cancer patients undergoing radical gastric resection were enrolled in this study.Homogeneity,discriminatory ability,and monotonicity of gradients in the modified 8th edition of the AJCC staging system and the 8th edition of the AJCC staging system alone were compared using linear trend χ2,likelihood ratio χ2 statistics,and Akaike information criterion(AIC)calculations.The Kaplan-Meier method and the log-rank test were used to analyze between-group differences in survival rate.Result The median follow-up time of the whole group was 58 months,and the average age of the whole group was 63.9 years(range 21-89 years).The 3-year and 5-year overall survival rates in N0 patients with lymphovascular invasion were lower than those in N0 patients without lymphovascular invasion(3-year OS: 78.3% vs 92.5%,5-year OS: 70.0% vs 88.3%,p<0.001).A multivariate analysis showed that age(p<0.001),lymphovascular invasion(p<0.001),and p T(p<0.001)were independent risk factors for the prognosis of N0 patients.Compared with the 8th edition of the AJCC staging system alone,the modified 8th AJCC staging system combined with lymphovascular invasion demonstrated a better linear trend χ2,likelihood ratio χ2 statistics,and AIC value(68.99 vs 58.58,70.18 vs 58.36,1473.38 vs 1485.04).In p T3N0M0 patients with lymphovascular invasion,the 3-year and 5-year overall survival rates of the adjuvant chemotherapy group were higher than those of the surgery alone group(3-year OS: 83.3% vs 68.2%,5-year OS: 72.3% vs 50.0%,p=0.048).Conclusion Lymphovascular invasion is an independent prognostic factor in N0 patients.The 8th AJCC staging system combined with lymphovascular invasion can improve the accuracy of the AJCC staging system for N0 patients.Moreover,adjuvant chemotherapy improves the survival of p T3N0M0 patients with lymphovascular invasion.