CDKN2A and cervical squamous intraepithelial neoplasia: Unlike colorectal cancers in that GD is an early event [9, 18, 24], we found, in the majority of ESCC tumors, GD likely occurred as a relatively late event, after CDKN2A/TP53 mutations and NLOH, suggesting that CIN occurs before GD in ESCC evolution.