CDKN2A and esophageal squamous cell carcinoma: Large-scale chromosomal deletions at 9p21.3 (CDKN2A) and 2q35 and amplifications at 11q13.3 (CCND1), 5p15.33, 8q24, 2q31.2 (NFE2L2), 8p11.23, 7q22.1 and 3q27 (SOX2) have been described in dysplastic esophageal tissues and are thought to be early events in ESCC carcinogenesis [18].