High expression of metadherin correlates with malignant pathological features and poor prognostic significance in papillary thyroid carcinoma

Background Metadherin (MTDH) protein, also called astrocyte elevated gene-1 (AEG-1) is over expressed in a variety of malignant tumours, and is closely related to tumour invasion and the poor prognosis. Objective This study tries to explore the clinical pathological significance of MTDH expression in a large cohort of patients with PTC. Design and patients Immunohistochemistry was used to detect MTDH expression in 156 cases of PTC, 6 cases of anaplastic thyroid carcinoma (ATC), 10 cases of multinodular goitre (MNG) and 10 cases of thyroid adenoma tissues who received a thyroid operation between June 2003 and July 2008. Measurements Clinical pathological data of 156 cases of PTC were analysed according to MTDH expression. The Kaplan-Meier method was used to plot survival curves and log-rank test to compare the postoperative survival results. The prognostic meaning of MTDH expression in PTC was evaluated by Cox regression analysis. Results The positive expression rates of MTDH in PTC and ATC tissues were 37.2% (58/156) and 50% (3/6), respectively, and MTDH positive expression rates were both 10% (1/10) in MNG and thyroid adenoma tissues. High MTDH expression in PTC was associated with larger tumour size (P = 0.030), high rates of lymph node (P = 0.041) and distant metastasis (P = 0.028), but no relation with the patient age, gender, tumour multicenter, extrathyroid invasion and tumour grade. High MTDH expression was associated with recurrence-free survival (RFS) and disease-specific survival rate (DSS) (P = 0.014, P = 0.001, respectively). Cox regression analysis showed that high MTDH expression was independent prognostic indicators for RFS and DSS in patients with PTC (P = 0.023 and P = 0.035, respectively). Conclusion High MTDH expression in PTC might play an important role in tumour growth and metastasis, and targeting MTDH treatment might have potential therapeutic value for patients with PTC.