A review of changes to and clinical implications of the eighth TNM classification of hepatobiliary and pancreatic cancers.

Abstract

Hepatobiliary and pancreatic cancers have poor outcomes. Clinical staging is useful for predicting survival and selecting treatment options. The 8th edition of tumor-node metastasis (TNM) was published in 2016 and came into effect from 2018. Regarding liver cancer (hepatocellular carcinoma), tumour size and vascular invasion were more emphasized adding numbers. Tumour size was included for intrahepatic cholangiocarcinoma. T2 for gallbladder cancer was divided into two categories based on the side of invasion, and lymph node metastasis was classified according to the number of lymph nodes, not the site. The N category for perihilar cholangiocarcinoma was changed to the same as that for gallbladder cancer (total number of regional lymph nodes). The depth of tumour invasion using cut-off values of 5 and 12mm was adopted as the T category for distal cholangiocarcinoma. The N category was also changed (the total number of regional lymph nodes). Regarding cancer of the ampulla of Vater, the T category was classified in more detail and the N category was also changed to the total number of regional lymph nodes. T1 for pancreatic cancer was separated into T1 subcategories (T1a, T1b and T1c) based on cut-off values of 5 and 10mm. T1-T3 were classified with cut-off values of ≤2cm, >2 to 4cm and >4cm. Furthermore, the N category was changed to the total number of regional lymph nodes. Although there are limitations due to treatment decisions only being based on imaging interpretation, this classification predicts the prognosis of patients more accurately than the previous edition.