['Tyrosine-protein phosphatase nonreceptor type 12 (PTPN12) is considered to be a tumor suppressor. It plays a significant role in human cancer, but its clinicopathologic and prognostic significance in esophageal squamous cell carcinoma (ESCC) has not yet been elucidated.', 'Using Western blot, we evaluated the PTPN12 expression in 20 pairs of surgically resected esophageal tissues. The PTPN12 was detected by immunochemistry in a tissue microarray from 260 surgically resected ESCCs, of which 260 were from primary cancer sites and 60 were from matched paracancerous normal tissues. Statistical analyses were applied to test the associations between PTPN12 expression, clinicopathologic factors, and prognosis.', 'Western blots showed that the expression level of PTPN12 was higher in normal paracancerous esophageal tissues than in ESCC tissues. By immunohistochemical analysis, high and low expression of PTPN12 was found in 62.1% and 37.9% of ESCCs, respectively. After multivariate analysis, along with pN status and tumor grade, the protein expression level of PTPN12 was an independent and significant predictive factor (p<0.001). Patients with PTPN12-high tumors had a longer disease-free survival and overall survival (p=0.002 and p=0.001, respectively), especially for those with stage II disease (both p<0.001).'] Is tyrosine-protein phosphatase nonreceptor type 12 a novel prognostic biomarker for esophageal squamous cell carcinoma?