Evaluation Of The Seventh American Joint Committee On Cancer Classification Of Gastric Adenocarcinoma In Comparison With The Sixth Classification

Objective:Gastric cancer is the most common malignant tumor of thedigestive system,now the incidence rates is No.4in the world, the globalannual increase of gastric cancer patients is about one million cases, thenumber of gastric cancer in China accounted for42%of the world. Thecurrent treatment of gastric cancer is surgery combined therapy, reasonablestaging system for assessing prognosis and guide treatment options havesignificant values.The world's most authoritative staging system of gastric cancer is theTNM staging system jointly developed by the AJCC and UICC. The sixthedition of TNM stage published in2002, the division of the lymph nodenumber is too general, the Ⅳ stage and Ⅲb stage overlaps with the5-yearsurvival rate has no significant difference statistically. In2010the seventhedition of TNM stage was published,make a larger adjustment in tumorinvasion and lymph node metastasis. This research will retrospectivelyanalysis the differences in the6,7edition staging and evaluate the clinicalsignificance and prognostic value.Methods:We have selected743patients' data with gastric carcinoma inThe Fourth Hospital of Hebei Medical University from January2007toDecember2008to review and study, The dates were input to database afterencoded. A follow-up study was carried out on the sample, the operation timewas looked as the starting point and the end point can be decided as the deathof the patient, lost in contact or the last time of diagnose. Ended by december31,2011.1All patients were restaged using the6th and7th editions of the UICCTNM staging systems, calculate and compare the two editions of the staging of the3-year survival and overall survival.2The likelihood ratio χ2test was used to measure homogeneity,thediscriminatory ability and monotonicity of gradient assessments weremeasured with the linear trend χ2test.3Calculate the Akaike information criterion of the6th and7th TNM stagingsystems.4Compare the-2log likelihood which is the parameter in the Coxregression of the6th and7th editions. The increase in the-2loglikelihoodstatistic on removal of any one staging system was in turn used as a means ofranking the individual staging systems according to their importance withinthe regression model.5Collecte possible factors influencing survival of these patients, by usingCOX proportional hazard model analysis, get the independent prognosticdeterminants of the gastric carcinoma.6All confirmed analyses data were performed and by using SPSS18.0software package. Chi-square test was used for the enumeration datacomparison, Overall survival rates were calculated according to the life-tablemethod, Kaplan-Meier was used for survival time analysis, All tests wereperformed at the0.05level of significances.Results:1Staging migrationIn the743cases of gastric cancer, in the two stage version a total of414cases (55.7%) have no change, and overall staging migration rate was44.3%.stage down of51cases (6.9%), stage raised of278cases (37.4%).2Comparation of T classificationThe T2stage in the6th edition system was subdivided into T2and T3inthe7th edition system, the T3and T4stage in the6th edition system wasdefined as T4a and T4b in the7th edition system. subgroups T2and T3havesignificantly difference, T4a and T4b don't have significantly difference.3Comparation of N classificationThe N1substage in the6th system was divided into N1and N2in the new system, and N2and N3substages were merged into N3. subgroups N1and N2have significantly difference, N3a and N3b also have significantlydifference.4Comparation of TNM staging4.1Comparation of stage IThe patients with6th TNM stage IB were reclassified to the patients with7th TNM stage IB and stage IIA, who had significantly different, patients with6th TNM stage IB reclassified to stage IIA and the rest of stage IIA in the7thedition system don't have significantly difference.4.2Comparation of stage IIThe patients with6th TNM stage II were classified to the patients with7th TNM stage IIA, stage IIB, and stage IIIA, who had significantly difference,patients with6th TNM stage II reclassified to stage IIIA and the rest of stageIIIA in the7th edition system don't have significantly difference.4.3Comparation of stage IIIThe patients with6th TNM stage IIIA were classified to the patients with7th TNM stage IIIA and stage IIIB, who don't have significantly difference.patients with6th TNM stage IIIB reclassified to stage IIIB and the rest ofstage IIIB in the7th edition system don't have significantly difference.4.4Comparation of stage IVthe patients with6th TNM stage IV were divided into the patients with7th TNM stage IIB, stage IIIA, stage IIIB, and stage IIIC, who hadsignificantly different.patients with6th TNM stage IIIB reclassified to stage IIIC and patientswith6th TNM stage IV reclassified to stage IIIC don't have significantlydifference.5Comprehensive comparisonThe criteria for evaluating the performance of the staging systems wereas follows:(1) homogeneity within subgroups (small differences in survivalamong patients within same stage),(2) discriminatory ability betweendifferent groups (greater differences in survival among patients in different stages), and (3) monotonicity of gradients shown in the association betweenstages and survival rates (patients with earlier stages have longer survival thanthose in later stages).5.1HomogeneityThe likelihood ratio χ2test was used to measure homogeneity, likelihoodratio χ2score of the6th TNM stage are185.088and197.974, likelihood ratioχ2score of the7th TNM stage are186.713and212.582.5.2Discriminatory abilityThe discriminatory ability was measured with the linear trend χ2test,linear trend χ2score of the6th TNM stage are162.620and174.965, lineartrend χ2score of the7th TNM stage are165.793and184.900.5.3Monotonicity of gradientsCalculate the1and3-year survival of T,N classification,TNM stage ofthe two editions,patients with earlier stages have longer survival thanthose inlater stages.5.4AIC testThe Akaike information criterion is an excellent measure of the statisticalmodel of a standard fitting,a smaller AIC value indicated a better model forpredicting outcome. AIC value of the6th TNM stage are3740.979and3702.485, AIC value of the7th TNM stage are3726.787and3687.608.5.5-2log likelihood and the increase in the-2log likelihood statistic onremoval of stage systemCompare the-2log likelihood which is the parameter in the Coxregression of the6th and7th editions.-2log likelihood score of the6th TNMstage are4139.286and4123.877,-2log likelihood score of the7th TNMstage are4134.395and4081.436.The increase in the-2loglikelihood statisticon removal of any one staging system was in turn used as a means of rankingthe individual staging systems according to their importance within theregression model. the6th and7th TNM stage increase35.137and40.028,respectively. 6COX analysis6.1Univariate analysisLesion sites,pathological types, tumor size, residual end, blood vesseland perineural involvement, degrees of nodes dissection, resection range, Tclassification, N classification, TNM stage of the6th and7th editions werethe significant prognostic factors to gastric cancer patients(P<0.05).6.2Multivariate analysisT classification(P=0.000), N classification(P=0.000), TNM stage(P=0.026)of the7th editions were the independent prognostic factors togastric cancer patients.Conclusion:1Adjustments in T staging, and take3lymph nodes as the cutoff point of7th N staging, and7th TNM staging were superior to the6th N stage.2More than7lymph nodes cutoff of N stage and definition of stage III wereinappropriate,the definition of stage IV in the AJCC7th system need furtherevaluation and improvement.3From a variety of statistical verification,7th TNM staging was superior tothe6th staging,7th TNM staging showed better performance in prognosis ofgastric cancer patients.