Delphian Lymph Node:A High-risk Factor For Cervical Lymph Node Metastasis Of Papillary Thyroid Carcinoma

Objective:The incidence of papillary thyroid microcarcinoma(PTMC)is increasing and is becoming a common clinical occurrence.The identification of central lymph node metastasis(CLNM)is crucial to the scope of surgery for patients with PTMC.Current studies have focused on finding better predictors to help assess the status of central lymph node(CLN).This study aims to investigate the correlation between delphain lymph node metastasis(DLNM)and the occurrence of cervical lymph node metastasis in PTMC patients,and whether DLN metastasis can be used as a predictor for clinical screening of PTMC patients at high risk of CLNM and for prophylactic central lymph node dissection(pCLND).The results of this study will provide a more reliable basis for pCLND.Methods:This single-centre retrospective study included the clinical data of 533 patients who underwent thyroid surgery at the Department of Thyroid Surgery,First Hospital of Shanxi Medical University between January 2021 and September 2022 and were pathologically diagnosed with PTMC,including basic information,preoperative ultrasound features,postoperative pathology and lymph node metastasis.The data were entered into statistical analysis software and divided into a CLN-positive group(216 patients)and a CLN-negative group(317 patients).The differences in clinicopathological factors between the two groups were compared,and the independent risk factors for the development of CLNM in PTMC were analysed by univariate analysis and multi-factor logistic regression,and the Receiver Operating Characteristic(ROC)curves were drawn.The ROC curves were then replotted by including DLNM as an independent variable,following the above steps.The differences between the two models were compared to clarify the intrinsic link between DLNM and CLNM.In the same way,the data were divided into lateral neck positive-metastases(56 cases)and lateral neck negativemetastases(477 cases)according to the status of the lateral lymph nodes(LLN),and risk factors affecting lateral lymph node metastases were analysed,and ROC curves were plotted and compared before and after DLNM inclusion.Results:The incidence of CLNM was 40.5%(216/533)in all patients and CLNM was statistically significantly correlated with specific clinicopathological features,including older age(>55 years),male,multifocality and tumor location(isthmus),and the probability of CLNM was higher in patients with DLN metastases(OR=9.258,95%CI:3.932-21.798).Comparison of the area under the ROC curve before and after the inclusion of DLN metastases showed that the area under the ROC curve was greater with the inclusion of DLN metastases(AUC:0.728,P<0.001).LLN metastasis was not significantly correlated with DLN metastasis(P>0.05),while it was correlated with CLN number(P<0.001).Conclusion:DLN metastases may help to predict the PTMC patient’s CLN involvement.In cases where CLN status is difficult to determine,intraoperative testing for DLN may be performed first to help determine CLN involvement,thereby reducing injury due to unnecessary CLN resection.When intraoperative frozen pathology results suggest a positive DLN,we recommend performing pCLND with protection of the parathyroid glands and the laryngeal recurrent nerve.