KRAS and colorectal adenocarcinoma: Previous studies have reported that the genetic characteristics of NECs in colorectum were more similar to that of colorectal adenocarcinoma, and the mutations of TP53, APC, KRAS, BRAF, and RB1 are the most common,4, 5 and TP53 mutations were not observed in well differentiated pancreatic NETs.12, 13