PIWIL4 and esophageal squamous cell carcinoma: The refined signature consists of 13 DE-ERGs—PIWIL4, SATB1, GSE1, NCOR1, BUB1, SAP30L, CHEK1, MASTL, ATM, BMI1, DNAJC2, UBE2D1, and SSRP1—each showing significant dysregulation in ESCC pathogenesis.