APC and Barrett esophagus: LOH in tumor suppressor gene loci, such as 17p (p53), 18q (DCC), 9p (CDKN2/p16), 5q (APC), and 10q (PTEN), has been reported to be a common genetic alteration in the metaplasia-dysplasia-carcinoma sequence in Barrett's esophagus [20,27-33].