CDKN2A and carcinoma of esophagus: In agreement with these findings, patients with idiopathic achalasia and chagasic megaesophagus, with or without esophageal carcinoma, showed reductions in expression of p16 protein [7] and Bellini et al. [33] observed a marginal decrease in p16 protein expression in chagasic megaesophagus.