Risk Factors And Predictive Model Of Central Lymph Node Metastasis In CN0 Papillary Thyroid Microcarcinoma

Objective: To probe the risk factors of central lymph node metastasis in cN0 papillary thyroid microcarcinoma patients,and build a Normogram model that can predict the probability of central lymph node metastasis.Methods: Record the clinical and pathological data of 192 patients with cN0 papillary thyroid microcarcinoma treated in Lanzhou University Second Hospital from1 Aug,2016 to 31 July,2020.Patients were divided into CLNM group and non-CLNM group according to whether the patient was confirmed to have CLNM by pathological report.Multivariate regression analysis was based on the rms software package in R4.0.3,and stepwise regression was applied to establish the nomogram model by contrasting the values of the AIC,compute c-index of the model,draw the ROC by the p ROC software package of R,and calculate the AUC.Bootstrap method was used to draw the calibration diagram,R language Resource Selection software package was used for goodness of fit test,rmda software package was used for DCA curve drawing,caret package was used to randomly select 25% of the patients from the original model sample,and Bootstrap method was used to draw the internal validation calibration diagram.Record the clinicopathological data of 59 patients with cN0 papillary thyroid microcarcinoma operated in the Lanzhou University Second Hospital from 1 Aug,2020 to 1 Dec,2020,the external validation calibration map was also drawn using the Bootstrap method,and the external validation correction map was drawn using the Predict ABEL software package in R language.In this study,statistical significance was accepted when P< 0.05.Results: Central lymph node metastasis discovered in 50 of 192 patients.Multivariate logistics regression showed that extratumoral invasion(P=0.032),presence of lymphadenopathy(P=0.010),and TG>68μg/L(P=0.007)were risk factors for central lymph node metastasis.Stepwise regression was used to establish the nomogram model.The model was established according to following risk factors:tumor diameter 0.5 ～ 1 cm,presence of extratumoral tissue infiltration,nodular goiter,presence of lymphadenopathy,and TG>68μg/L,the c-Index and AUC were 0.711,demonstrating that the model’s prediction ability is relatively well.The calibration graph construction results suggest that the nomogram has good calibration,and the drawing result of DCA curve prove that the effective prediction interval of the nomogram model is set as the threshold probability range of 10.6% ～ 62.5%.The result of internal validation calibration plot demonstrated that the nomogram have good consistency,the results of external validation calibration plot and correction plot demonstrated the good model applicability.Conclusion: The results of this study suggest that extratumoral invasion,lymphadenopathy,and TG > 68 μg/L are risk factors with CLNM in patients with cN0 PTMC,and the nomogram model established in the study can effectively predict the probability of CLNM in patients with cN0 PTMC and help doctors to develop a diagnosis and treatment plan.However,due to the small amount of data in this study and the single-center study,its applicability and reliability still need to be verified in subsequent studies.