High Expression of Yes-activated Protein-1 in Papillary Thyroid Carcinoma Correlates With Poor Prognosis.

Context: The Hippo signal transduction pathway is highly conserved in mammals. It plays a critical role in tissue and organ size by regulating the balance between cell proliferation and apoptosis. However, there have been few reports concerning Yes-activated protein-1 (YAP-1) elevation in papillary thyroid cancer (PTC). Objective: The objective of this study was to determine whether YAP-1 expression is a biomarker and high-risk clinicopathologic prognosticator in PTC. Design: A large series of patients of PTC with a long follow-up were investigated for YAP-1 expression. Setting: Our study was carried out in the laboratory of breast and thyroid and Department of pathology. Patients or Other Participants: Immunohistochemical staining was performed on 240 patient-derived PTC specimens to analyze the correlation of YAP-1 expression with clinicopathologic features and prognosis in patients with PTC. Intervention: The 240 PTC patients were immunohistochemically assessed for YAP-1 expression. Outcome Measures: Kaplan-Meier analysis was conducted to assess recurrence-free survival (RFS). Univariate and multivariate analyses were conducted to determine prognosticators of RFS. Results: YAP-1 expression was observed in 62.1% of PTC tumors. There were significant positive correlations between YAP-1 expression and tumor size, lymph node metastases, extrathyroidal extension, and tissue infiltration. YAP-1 expression was significantly associated with RFS. Univariate analysis revealed that YAP-1 expression significantly affects RFS. YAP-1 and extrathyroidal extension were significant independent prognosticators for RFS. Conclusions: YAP-1 expression was significantly correlated with high-risk clinicopathologic features and inferior RFS in patients with PTC.