Hepatocellular carcinoma (HCC) is the fifth most common malignancy in the world and the third most common cause of death due to cancer in Korea. There are several treatments of choice for HCC, and hepatic resection is a good modality for treatment. The use of a staging system is essential to predict the prognosis and to assess the outcome of HCC after treatment. Even so, there is no set consensus on the best HCC staging system. The prognostic factors of HCC include tumor factors such as the number of tumors, size, vessel invasion, adjacent organ invasion, lymph node metastasis, and distant metastasis, as well as the biologic characteristics of tumor-differentiation, rapidity and pattern of growth. Because HCC, unlike other tumors, is associated with underlying liver diseases such as liver cirrhosis, liver function is also considered a significant prognostic factor.
Several systems have been introduced as guidelines for the prediction of HCC prognosis. The staging systems currently used can be divided into two categories: those that evaluate only tumor characteristics, such as the tumor node metastasis system of the American Joint Committee on Cancer (AJCC) and those that add liver function status to tumor characteristics, such as the Okuda classification, the Barcelona Clinic Liver Cancer (BCLC) classification, the Japan Integrate Staging (JIS) score (8), the Cancer of the Liver Italian Program (CLIP) system, the Group d'Etude de Traitement du Carcinoma Hepatocellulaire (GRETCH) system, and the Chinese University Prognostic Index (CUPI) classification. The various staging systems differ in their predicted prognoses, and which system is the best remains a controversial issue. HCC arises in chronic liver diseases often with hepatic insufficiency that may affect survival. Patients undergoing hepatic resection have better preserved liver function than the patients treated with other modalities. Therefore, we focused the AJCC system and compared 8th edition with 7th edition.



Major changes can be described as follows.
For example, single tumor with vascular invasion had been categorized as T2 in the AJCC 7th, but in the AJCC 8th, if the size of tumor is less than 2cm despite the presence of vascular invasion, it is categorized as T1a. There is a minimal improvement in discriminating value for the 8th edition compared to the 7th edition; however, notable overlap in outcomes is still observed between stages IB/II and IIIB/IVA. A modified AJCC 8th system collapsing these overlapping stages may be more clinically relevant. Future revisions should consider substratification of early HCC, specifically by distinguishing solitary tumors >2 cm from multifocal tumors ≤5 cm, and by considering the prognostic impact of vascular invasion in multifocal tumors ≤5 cm.