Comparison Of Four Lymph Node Staging Schemes For Prognostic Value In Medullary Thyroid Carcinoma

Background and objectiveLymph node metastasis is an important factor affecting the prognosis of medullary thyroid cancer(MTC),but the existing lymph node staging system of MTC is not accurate,only according to the presence of positive lymph nodes and the location of lymph node metastasis,it can be divided into NO stage(no positive lymph nodes).Stage Nla(central region lymph node metastasis)and Stage N1b(cervical region lymph node metastasis)do not take into account the specific situation of lymph node metastasis.Several improved lymph node staging schemes have recently been proposed:Number of positive nodes(NPLN)stage,positive node ratio(LNR)stage and log odds of positive lymph nodes Nodes(LODDS)staging can more accurately reflect the specific situation of lymph node metastasis.The purpose of this study was to select the most suitable lymph node staging system for evaluating the prognosis of MTC patients by comparing the prognostic differentiation ability,intergroup heterogeneity and intra-group heterogeneity of LNR,LODDS,NPLN and existing AJCC N staging schemes.Methods1380 MTC patients were screened from SEER database for retrospective analysis.Univariate and multivariate Cox regression analysis were used to screen the independent risk factors for MTC patients.By calculating Harrell’s Concorindex(Cindex)and AUC(Area under the Receiver Operating Characteristic Curve)values,The prognostic differentiation ability of different lymph node staging schemes was compared.Kaplan-meier method was used to calculate the survival differences between different groups,and log-rank test was used to compare the survival differences between different groups.Results1.Multivariate COX regression analysis showed that AJCC N stage,NPLN stage,LNR stage and LODDS stage were independent risk factors for MTC specific survival.2.LNR staging had higher C index and AUC values and lower AIC values than NPLN,LODDS and AJCC N staging systems,and the NRI and IDI values of LNR staging model were both bigger than 0 when compared with other lymph node staging schemes,indicating that LNR staging had better predictive differentiation ability3.When selected LNR stage was used for grouping analysis of the other three lymph node staging schemes,there were significant differences in prognosis among different LNR groups(P<0.05).However,when selected NPLN,LODDS and AJCCN stage for grouping analysis of LNR,the prognosis was similar among all groups except LNR2 stage(P>0.05).Compared with the other three lymph node stages,LNR stage had higher inter-group heterogeneity and intra-group homogeneity.4.Group analysis of LNR,LODDS and NPLN stages related to the number of positive lymph nodes was conducted according to the number of lymph nodes dissected.It was found that the prognosis of different groups with different number of lymph nodes dissected was similar in LNR stage(P>0.05),while intra-group heterogeneity was observed in the other two lymph node stages(P<0.05).Further,LNR staging showed high intra-group homogeneity.ConclusionLNR staging had better prognostic differentiation ability,greater inter-group heterogeneity and less intra-group heterogeneity than the other three lymph node staging schemes.Therefore,LNR staging is recommended as the best lymph node staging scheme to evaluate the prognosis of MTC patients.