Abstract: Objective To detect the expression of serum hyaluronic acid synthetase 2 (HAS2),carcinoembryonic antigen (CEA) and cytokeratin 19 (CK-19) in different pathologic types of thyroid carcinoma,and to explore their diagnostic value and prediction value for postoperative recurrence.Methods A total of 202 patients who received surgical treatment for thyroid cancer in our hospital from January 2017 to January 2022 were selected and divided into differentiated group (164 cases) and undifferentiated group (38 cases).All patients were followed up for a minimum of 3 months,a maximum of 85 months,and a median of 38 months.In the differentiated group,157 patients survived,of whom 66 had recurrent thyroid cancer and 91 did not.In the undifferentiated group, 37 cases died and 1 case survived. The surviving patients relapsed during the follow-up period.Clinical data of patients were collected,serum HAS2,CEA and CK-19 levels were detected,and the correlation between serum HAS2,CEA and CK-19 levels in different types of thyroid cancer was analyzed.Receiver operating characteristic curve (ROC) was used to analyze the value of serum HAS2,CEA and CK19 levels in the diagnosis of thyroid cancer classification and the prediction value of differentiated thyroid cancer recurrence.Results The proportion of females in the differentiated group was higher than that in the undifferentiated group.The proportion of TNM stage Ⅳ patients,mean age,serum CEA and CK-19 levels were lower than those in undifferentiated group (P<0.05).Serum CEA and CK-19 levels were positively correlated with undifferentiated thyroid cancer (r=0.593,r=0.150,P<0.05).The area under the curve (AUC) of HAS2,CEA,CK19 in the combined evaluation of undifferentiated thyroid cancer was 0.609,0.859,0.595,0.879,and the Yoden index was 0.278,0.625,0.195,0.619,respectively.The combined prediction AUC of HAS2,CEA,CK19 and three indexes for the recurrence of differentiated thyroid cancer was 0.712,0.819,0.671 and 0.870,respectively,and the Yoden index was 0.374,0.557,0.311 and 0.616,respectively.Conclusion Serum HAS2,CEA and CK-19 have certain values for the classification diagnosis of undifferentiated thyroid and the recurrence of differentiated thyroid cancer, and can be used as auxiliary predictive indicators.

Key words: hyaluronic acid synthase 2; carcinoembryonic antigen; cytokeratin 19; thyroid cancer; recrudescence