TP53 and small intestine adenocarcinoma: In particular, TP53 mutations have been identified in only 5% of NADAs by Ota et al. [16], while recent studies indicate that TP53 (38–58%), KRAS (27–54%), and APC (11–27%) are the most frequently mutated genes in small bowel adenocarcinomas [9,10,11,20], suggesting that this molecular alteration is a late event in tumorigenesis.