Abstract: Objective To investigate the expression of cytokeratin-20 （CK-20） and galectin-4 （LGALS4） in papillary thyroid carcinoma and its clinical significance. Methods A total 128 patients with pathologically confirmed papillary thyroid carcinoma who were operated in the First Hospital of Zhangjiakou from January 2010 to June 2014，were selected as the investigated subjects，from whom surgical cancer tissues and the corresponding adjacent normal tissues were collected. The expressions of CK-20 and LGALS4 was detected by immuno-histochemistry；the diagnostic value of CK-20 and LGASL4 in papillary thyroid carcinoma was analyzed by the ROC curve；the influence factors of disease-free survival（DFS） was analyzed by multivariable Cox regression. Results The positive expression rate of CK-20 in papillary thyroid carcinoma was higher than that in adjacent normal tissues，while the expression of LGALS4 was lower than that in adjacent normal tissues（all P<0.005）. The high expression of CK-20 and low expression of LGALS4 were related to distant tumor metastasis，TNM stage，and lymph node metastasis （all P<0.05），and CK-20 expression was negatively correlated with LGALS4 expression level （r=-0.531，P<0.001）. The area under the curve and sensitivity of the combined diagnosis of CK-20 and LGALS4 in thyroid papillary carcinoma was better than their single diagnosis （all P<0.05）. The 5-year DFS of patients with CK-20 positive expression was lower than that of negative expression patients，while the 5-year DFS of LGALS4 positive expression patients was higher than that of negative expression patients （all P<0.05）. The high expression of CK-20，distant metastasis and lymph node metastasis were independent risk factors for DFS，but high expression of LGALS4 was a protective factor for DFS（all P<0.05）. Conclusions The expression of CK-20 and LGALS4 in papillary thyroid tissues is negatively correlated. High expression of CK-20 indicates a poor prognosis，while high expression of LGALS4 indicates a good prognosis，and both are expected to become biomarker molecules for monitoring the prognosis of papillary thyroid carcinoma.

Key words: Papillary thyroid carcinoma, Cytokeratin-20, Galectin-4, Diagnosis, Biomarkers