The Series Study Of The Impact Of Lymph Node Metastatic Rate On The Clinical Outcome In Papillary Thyroid Cancer

Lymph node metastasis can be common seen in papillary thyroid cancer(PTC)with a high occurrence of 20%~50%,which also give rise to the high recurrence and mortality.In Part 1,clinical response was used as an outcome parameter to evaluate the predictive value of lymph node metastasis ratio(LR)as a prognostic indicator.While in Part 2,distant metastasis(DM)was similarly applied as an outcome parameter to evaluate the predictive value of LR as a prognostic indicator.In Part 3,the comparison of LR and the number of metastatic lymph nodes(LNs)in predicting clinical response(ER)was further investigated in PTC specifically.Here are the three parts as follows:Part 1: The impact of LR on clinical response of radioiodine therapy in PTC Objective: To investigate the relationship between lymph node metastatic rate(LR)and clinical response to radioiodine remnant ablation in PTC.Methods: 143 PTC patients after radioiodine remnant ablation were included in the study,and they were classified into four groups [Ⅰ(0%-10%),Ⅱ(>10%-25%),Ⅲ(>25%-50%),Ⅳ(>50%)] according to the LR.The clinical response to initial radioiodine remnant ablation after a median follow-up period of 20.7 months were evaluated,which were classified into four groups [excellent response(ER),indeterminate response(IDR),biochemical incomplete response(BIR),structural incomplete response(SIR)] according to guideline proposed by 2015 American Thyroid Association.One-Way analysis of variance,χ2test and Kruskal-Wallis test were used to evaluate the statistical differences of basic clinicopathological features and clinical response among the four groups.Furthermore,the receiver operating characteristic curve(ROC)were analyzed to evaluate the clinical value of LR for predicting ER and optimal cut-off point.Results: There were no significant differences in gender and T-stage among four groups(P>0.05),but the age of group I was significantly older than the other three groups(F=6.114,P=0.001).With the increase of LR,the number of ER case decreases,while cases of BIR and SIR generally rise.Comparing with the other three groups,less cases of ER(27.8%),while more BIR(27.8%)or SIR(11.1%)were observed in group Ⅳ(H=18.816,P=0.000).Cut-off value of lymph node involved rate was 52.27%,with a better specificity of predicting ER(OR=10.011,P=0.000).Area under the ROC curve was 0.668.Conclusion: The higher LR in patients with PTC,the worse clinical outcome it could be.A cut-off of LR 52.27% was a specific independent predictor for the clinical outcome in PTC patients treated with radioiodine remnant ablation.Part 2: The impact of LR on clinical response of radioiodine therapy in PTC Objective: To investigate the relationship between LR and DM in PTC patients,and its potential value in predicting the risk of DM.Methods: PTC patients were divided into two groups as M0(121 cases)and M1(41 cases)according to the presence of distant metastases or not.T-text and χ2 test were used to evaluate the statistical differences of basic clinicopathological features between the two groups;Multivariate analysis was used to quantify LR as an independent factor of DM.The ROC curve was employed to evaluate the clinical value of LR and LNs for predicting DM and optimal cut-off point respectively.The cumulative risk of distant metastasis curves according to the LR and LNs status were constructed with the Kaplan–Meier method,and the log rank test was used to compare these curves.Results: There were no statistical differences in age and multifocality between two groups(P>0.05),while gender,extrathyroidal invasion and tumor size were significantly different.LR is an independent indicator for predicting DM(OR=1.133,P=0.000).An increase of LR was significantly associated with DM and patients with more than 15 involved LNs had the steepest increasing pattern in the cumulative risk of DM compared with those involved LN less than 15(P=0.002).Conclusions: LR may be an independent predictive marker for distant metastases in PTC,and might be more potential when LNs was combined as an adjuvant factor.Part 3: Comparison of LR and LNs in predicting clinical response in PTC patients Objective: To compare the prognostic value of LR and the number of metastatic LNs on clinical response in PTC.Methods: A total of 384 PTC patients with lymph node(LR)metastases were enrolled in this study,all of whom underwent total or near total thyroidectomy and subsequent radioiodine ablation.After a mean follow-up of 25.7 months,response to initial therapy was classified as ER,IDR,BIR or SIR.ROC curve was respectively employed to evaluate and compare the clinical value of the number of metastatic LNs and LR for predicting ER in different number of dissected LNs(DLNs).Multivariate analyses were further performed to explore the indicator for ER.Results: In patients with ≤10 DLNs,LR presented higher area under the ROC curve(AUC)than the number of metastatic LNs in predicting ER(LR: 0.687,LNs: 0.556,P=0.02),while it turns opposite in those with >10 DLNs.In the multivariate analysis,LR(OR=1.037,P=0.001)rather than the number metastatic LNs(OR=0.752,P=0.09)was an independent indicator for ER in addition to preablative stimulated thyroglobulin(ps-Tg,OR=1.056,P=0.01)among patients with ≤10 DLNs.While in patients with >10 DLNs,the number of metastatic LNs(OR=1.062,P=0.04)turned to be independent factor for ER,apart from ps-Tg(OR=1.071,P=0.00)and gender(OR=0.570,P=0.02).Conclusions: LR appears to be a better negative predictor for ER than the number ofmetastatic LNs in PTC patients with≤10 DLNs,while the number of metastatic LNs is superior to LR in those with >10 DLNs.