Abstract: Objective To explore the clinical application of serum specific miRNAs in the diagnosis of thyroid papillary carcinoma. Methods Ninety-two patients with papillary thyroid cancer admitted to our hospital from January 2017 to May 2019 were selected as the study group.In the same period, 92 healthy people served as control group, while 92 benign thyroid tumors patients served as benign group.Total RNA was extracted from serum samples of all subjects,and the relative expression levels of microRNA-221, microRNA-222 and microRNA-455 were detected by fluorescence quantitative PCR.The expression of three kinds of microRNAs in three groups of subjects was compared.The expression of three kinds of microRNAs in patients with different clinicopathological characteristics in the study group was compared, and the diagnostic efficacy of the three kinds of microRNAs was analyzed by ROC working curve. Results The serum levels of three kinds of miRNAs in the study group were significantly higher than those in the control group; the expressions of miRNAs-455 were significantly higher in patients over 45 years old, with tumors larger than 1 cm, with single lesion and with extraglandular invasion; the expressions of miRNAs-221 and miRNAs-222 were significantly higher in patients with lymph node metastasis and extraglandular invasion.The above results were all P<0.05.The expression of miRNA-221, miRNA-222 and miRNA-455 in the diagnosis of papillary thyroid cancer were 0.813, 0.802 and 0.794, respectively. Conclusion The expression of serum miRNA-221, miRNA-222 and miRNA-455 in patients with thyroid papillary cancer is significantly increased. The expression of miRNAs can reflect the lesion, metastasis and infiltration of cancer. Serum-specific miRNAs has certain value in the diagnosis of thyroid papillary cancer, but the sensitivity and specificity of the diagnosis still need further study.

Key words: papillary thyroid cancer, serum specific miRNAs, diagnosis