PTGS2 and esophageal cancer: The upregulated expression of COX-2 has been observed in numerous premalignant and malignant diseases, including colorectal adenoma, Barrett’s esophagus, colorectal cancer, gastric cancer, esophageal cancer, breast cancer, lung cancer, glioblastoma and so on (Wang and Dubois, 2006; Jiang et al., 2017; Wang D. et al., 2021).