ESR1 and esophageal squamous cell carcinoma: The immunohistochemical expression levels of p53, p21waf1, molecular immunology borstel-1 (MIB-1, Ki-67), p16INK4A, cyclin D1, E-cadherin, Bcl-2, tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB, transforming growth factor (TGF)-β, matrix metalloproteinase (MMP)-7, cyclooxygenase (COX)-2, epidermal growth factor receptor (EGFR), human EGFR type 2 (HER2/neu), estrogen receptor (ER) and hypoxia-inducible factor (HIF)-1α were studied in 10 cases of ESCC treated with CCRT.