Risk Assessment About Central Lymph Node Metastasis Of Papillary Thyroid Microcarcinoma

Objective The risk factors of central lymph node metastasis(CLNM)in clinical lymph node negative(cN0)papillary thyroid micro-carcinoma(PTMC)were analyzed.The CLNM risk score system was initially established to provide a theoretical basis for decision-making of prevention central lymph node dissection.Method From 2013 to 2015,500 patients with cN0-stage PTMC who were underwent surgery for the first time were selected as the model group.The clinical and pathological data were collected.According to postoperative pathological results were divided into CLNM positive group and negative group.Univariate analysis were used to screen for statistically significant risk factors.Logistic regression analysis were used to determine the relevant independent risk factors.Then based on the risk factors' Odds ratio(OR value)and Logistic regression equation,the CLNM risk score system was initially established.The score system was further established by area under receiver operating characteristic curve(ROC)curve and HosmerLemeshow goodness of fit tests.From January 2017 to December 2017,PTMC patients as a validation group to evaluate the reliability of the risk score system.Results 500 patients with cN0 stage PTMC in the model group,the rate of lymph node metastasis in the central area was 28.4%.Logistic regression analysis showed that male(OR=1.924,P=0.011),the maximum diameter of tumor was ?0.5 cm(OR=2.844,P=0.037),tumor invasion outside the gland(OR=3.721,P=0.004),the border is unclear(OR=1.674,P=0.039),the tumor with calcification(OR=1.801,P=0.007),aspect ratio?1(OR=2.056,P=0.001)is the independent risk factors for CLNM of PTMC.Based on the above six indicators,the scores were classified as low risk according to score ?5,moderate risk 6 to 8 and high risk at 9 or higher.A risk assessment system was established.The area under receiver operating characteristic curve(ROC)was 0.687(95% CI:0.635-0.783).Hosmer-Lemeshow statistic test was P=0.888.According to the risk assessment system,164 PTMC patients in the validation group were scored.Among the low-risk group,the moderate-risk group and the high-group,96.8%,58.1% and 43.2% were the CLNM-negative patients,and 3.1%,41.9% and 65.8% were CLNM-positive patients respectively.The area under ROC was 0.837(95% CI:0.778-0.869).Conclusion The risk assessment system established in this study has a certain diagnostic value,which can provide a theoretical basis for intraoperative decision-making in preventive central lymph node dissection and guide clinical work.According to the risk assessment system,low-risk patients do not recommend prophylactic central lymph node dissection.High-risk patients are recommended central lymph node dissection,while moderate-risk patients are advised to make decisions based on the surgeon's ability to perform surgery,the patient's overall condition and the individual's wishes.