| C15 | Malignant neoplasm of esophagus |
| C15.3 | Malignant neoplasm of upper third of esophagus |
| C15.4 | Malignant neoplasm of middle third of esophagus |
| C15.5 | Malignant neoplasm of lower third of esophagus |
| C15.8 | Malignant neoplasm of overlapping sites of esophagus |
| C15.9 | Malignant neoplasm of esophagus, unspecified |
| C16 | Malignant neoplasm of stomach |
| C16.0 | Malignant neoplasm of cardia |
| C16.1 | Malignant neoplasm of fundus of stomach |
| C16.2 | Malignant neoplasm of body of stomach |
| C16.3 | Malignant neoplasm of pyloric antrum |
| C16.4 | Malignant neoplasm of pylorus |
| C16.5 | Malignant neoplasm of lesser curvature of stomach, unspecified |
| C16.6 | Malignant neoplasm of greater curvature of stomach, unspecified |
| C16.8 | Malignant neoplasm of overlapping sites of stomach |
| C16.9 | Malignant neoplasm of stomach, unspecified |
| C17 | Malignant neoplasm of small intestine |
| C17.0 | Malignant neoplasm of duodenum |
| C17.1 | Malignant neoplasm of jejunum |
| C17.2 | Malignant neoplasm of ileum |
| C17.3 | Meckel's diverticulum, malignant |
| C17.8 | Malignant neoplasm of overlapping sites of small intestine |
| C17.9 | Malignant neoplasm of small intestine, unspecified |
| C18 | Malignant neoplasm of colon |
| C18.0 | Malignant neoplasm of cecum |
| C18.1 | Malignant neoplasm of appendix |
| C18.2 | Malignant neoplasm of ascending colon |
| C18.3 | Malignant neoplasm of hepatic flexure |
| C18.4 | Malignant neoplasm of transverse colon |
| C18.5 | Malignant neoplasm of splenic flexure |
| C18.6 | Malignant neoplasm of descending colon |
| C18.7 | Malignant neoplasm of sigmoid colon |
| C18.8 | Malignant neoplasm of overlapping sites of colon |
| C18.9 | Malignant neoplasm of colon, unspecified |
| C19 | Malignant neoplasm of rectosigmoid junction |
| C20 | Malignant neoplasm of rectum |
| C21 | Malignant neoplasm of anus and anal canal |
| C21.0 | Malignant neoplasm of anus, unspecified |
| C21.1 | Malignant neoplasm of anal canal |
| C21.2 | Malignant neoplasm of cloacogenic zone |
| C21.8 | Malignant neoplasm of overlapping sites of rectum, anus and anal canal |
| C22 | Malignant neoplasm of liver and intrahepatic bile ducts |
| C22.0 | Liver cell carcinoma |
| C22.1 | Intrahepatic bile duct carcinoma |
| C22.2 | Hepatoblastoma |
| C22.3 | Angiosarcoma of liver |
| C22.4 | Other sarcomas of liver |
| C22.7 | Other specified carcinomas of liver |
| C22.8 | Malignant neoplasm of liver, primary, unspecified as to type |
| C22.9 | Malignant neoplasm of liver, not specified as primary or secondary |
| C23 | Malignant neoplasm of gallbladder |
| C24 | Malignant neoplasm of other and unspecified parts of biliary tract |
| C24.0 | Malignant neoplasm of extrahepatic bile duct |
| C24.1 | Malignant neoplasm of ampulla of Vater |
| C24.8 | Malignant neoplasm of overlapping sites of biliary tract |
| C24.9 | Malignant neoplasm of biliary tract, unspecified |
| C25 | Malignant neoplasm of pancreas |
| C25.0 | Malignant neoplasm of head of pancreas |
| C25.1 | Malignant neoplasm of body of pancreas |
| C25.2 | Malignant neoplasm of tail of pancreas |
| C25.3 | Malignant neoplasm of pancreatic duct |
| C25.4 | Malignant neoplasm of endocrine pancreas |
| C25.7 | Malignant neoplasm of other parts of pancreas |
| C25.8 | Malignant neoplasm of overlapping sites of pancreas |
| C25.9 | Malignant neoplasm of pancreas, unspecified |
| C26 | Malignant neoplasm of other and ill-defined digestive organs |
| C26.0 | Malignant neoplasm of intestinal tract, part unspecified |
| C26.1 | Malignant neoplasm of spleen |
| C26.9 | Malignant neoplasm of ill-defined sites within the digestive system |