PIWIL2 and esophageal squamous cell carcinoma: To reveal the correlation between PIWIL2 and clinicopathological indexes and prognosis of ESCC, TMAs consist of 109 ESCC patients were subjected to immunohistochemistry (IHC) and the expression for PIWIL2 was scored by multiplying intensity value (0–3) and percentage of staining area (0–4).