External validation of subclassification system and progression pattern analysis in hepatocelluar carcinoma with macroscopic vascular invasion

Background and purpose: The present study aimed to validate the performance of a previously proposed subclassification model to predict prognosis after combined transarterial chemoembolization (TACE) and external beam radiotherapy (RT) for hepatocellular carcinoma (HCC) with macrovascular invasion (MVI) in an independent cohort that received the same first-line treatment for the patients with the similar disease extent characteristics, and analyzed the progression patterns as well as progression-free survival (PFS). Materials and methods: This study was conducted using prospectively collected data from the XXXXX HCC registry for newly diagnosed, previously untreated HCC between 2005 and 2018. Finally, 417 patients who satisfied the eligibility criteria were included and analyzed. Results: The median PFS and overall survival (OS) were 5.2 and 13.9 months, respectively. Similar to a previous study, subclassification of patients into very low-, low-, intermediate-, and high-risk groups showed a median OS of 98.4, 18.3, 9.7, and 5.8 months, respectively (P < 0.001). Additionally, subclassification of patients into the very low-, low-, intermediate-, and high-risk groups showed median PFS of 18.7, 6.7, 3.3, and 2.3 months, respectively (p < 0.001). Overall, intrahepatic progression was the most common pattern of progression; however, extrahepatic progression was more common in the intermediate- and high-risk groups. Conclusion: The previously proposed subclassification model was successfully validated in an independent cohort. Treatment modification should be considered in the intermediate- and high-risk patient groups because of their frequent extrahepatic as well as intrahepatic progressions after combined TACE and RT.