CDKN2A and esophageal squamous cell carcinoma: Although several studies have evaluated biallelic loss/homozygous deletion within specific genes in tumors (e.g., CDKN2A [25]), including ESCC [26], using techniques such as FISH, only a few prior reports have used genome-wide techniques such as SNP or comparative genomic hybridization (CGH) arrays to agnostically assess homozygous deletions in tumor cell lines or tissues.