CDKN2A and esophageal squamous cell carcinoma: The study aimed to explore the associations between the interactions of serum vitamin B2 or B12 levels, aberrant DNA methylation of p16 or p53 and MTHFR C677T polymorphism and the risks of esophageal squamous cell carcinoma (ESCC) and esophageal precancerous lesion (EPL).