There are numerous digestive organs that are given distinctive codes. C15-21 run through the gastrointestinal tract from oesophagus to anus, whereas C22-25 deal with hepatic, biliary and pancreatic structures.
The oesophagus is coded as C15. It can be divided into cervical, thoracic and abdominal parts (C15.0, C15.1 and C15.2) or upper, middle and lower thirds (C15.3, C15.4, C15.5). Tumours of the gastro-oesophageal junction are classified as C16.0 (cardia of stomach).
A common radiation oncology code. Tumours of the rectosigmoid junction are C19 (above). Tumours which can not be identified as rectal or anal due to location at the anorectal junction should be classified as C21.8 (below). There are no subclassifications for C20 which is a shame as it would be useful to identify upper, mid, and lower rectal cancers for retrospective research.
Much like the haematological malignancies, liver and intrahepatic biliary tumours are classified by the histological subtype. Hepatocellular carcinoma is C22.0. Intrahepatic cholangiocarcinoma is C22.1. Hepatoblastoma is C22.2. Angiosarcoma is C22.3. Other primary liver sarcomas are C22.4 and other carcinomas are C22.5. Other specified malignant neoplasms are C22.7, whereas unspecified lesions are C22.9.
The most common liver tumour, secondary metastases, are C78.7.
There are no special sub sites for the gallbladder.
Extrahepatic bile ducts themselves are C24.0, whereas the ampulla of Vater is C24.1. Lesions that overlap the biliary tree structures is C24.8.