To Evaluation The6th/7th Edition AJCC/UICC TNM Calssification For Gastric Adenocarcinoma: Proposal Of A New Staging System

Objective:To compare the prognostic significance of the seventh edition TNMstaging classification for gastric adenocarcinoma with the sixth edition.To evaluatethe prognostic significance of metastatic lymph node ratio in gastric cancer.Topropose a new staging system-based on the seventh edition TNM staging system.Methods:This study includes772gastric cancer patients who underwentsurgical resection in ChangHai Hospital and were staged using the6th and7theditionstaging systems respectively. We conducted crude survival analysis, univariate andmultivariate analyses according to the different staging systems. Homogeneity,discriminatory ability, and monotonicity of gradients of the two systems werecompared using linear trend χ2test, likelihood ratio χ2test, and Akaike informationcriterion (AIC) calculations. We employed ROC curves to evaluate the predictiveaccuracy. The correlation between NexLN and metastatic lymph nodes was analyzedby using Spearman’s correlation analysis.Results: In the trial,401patients of the total1110patients who underwent thesurgery for gastric cancer had more than15lymph nodes examinated and371patients had less than15lymph nodes examinated. Significant differences in overallsurvival were observed according to the T，N and M substages using the6th/7thedition AJCC TNM staging system．The Kaplan-Meier survival curves showed agood discriminatory ability among stagesⅠ through Ⅳ in bothof the6th and7thedition staging systems(P=0.000)．There were similar survival curves betweensubstages Ⅰ A and ⅠB (P=0．643)， ⅠB and ⅡA (P=0．267)， ⅡB andⅢ A(P=0．534)，Ⅲ A and ⅢB (P=0．124)，and Ⅲ B and ⅢC (P=0．174) when thepatients were classified into eight substages according to the7th edition AJCC TNMstaging system．The7th edition T classification and N classification were superior tothe6th edition. The6th edition system had higher linear trend and likelihood ratioχ2scores, and smaller AIC values compared with those for the7th edition, whichrepresented the optimum prognostic stratification. There was correlationship betweenNexLN and metastatic lymph nodes(r=0.374，P=0.000). After the LNR classificationreplace the7th version, it was found that the new system was better than the7thedition. For the reason of that there were not significant different among some of theeight substages according to the7thedition，we reclassified the TNM system on thebasis of the7thedition. The new system had6substages and the Kaplan-Meiersurvival curves showed a good discriminatory ability among these substages. The new staging system had a smaller AIC.Conclusion: Our study suggests that T/N classification of the7th edition systemperforms better than the6th edition. However, the6th edition can exactly predict theprognosis for gastric cancer patients. LNR seems to be an accurate staging system canavoid staging migration in the situation of T4. The new staging system seems toprovide optimal prognosis.