Identifying Clonal Origin of Multifocal Hepatocellular Carcinoma and Its Clinical Implications.

Hepatocellular carcinoma (HCC) is characterized by high prevalence of multifocality. Multifocal HCC can arise synchronously or metachronously either from intrahepatic metastasis (IM) or multicentric occurrence (MO). To date, there have been no established criteria to accurately distinguish whether multifocal HCC originates from IM or MO. Histopathological features remain the most convenient strategy but with subjectivity and limited accuracy. Various molecular biological techniques involving assessment of TP53 mutation status, hepatitis B virus integration sites, and chromosomal alterations have been applied to determine the clonal origin. The introduction of next-generation sequencing facilitates a more comprehensive annotation of intertumor heterogeneity, resulting in more sensitive and accurate clonal discrimination. Generally, MO-HCC has better overall survival than IM-HCC after curative resection. Adjuvant antiviral treatment has been proved to decrease post-treatment recurrence probably by reducing MO-HCC recurrence, whereas adjuvant sorafenib treatment targeting prior micrometastasis failed to reduce IM-HCC recurrence. Recent studies recommended transcatheter arterial chemoembolization (TACE) and traditional Chinese medicine Huaier granule as effective adjuvant treatments probably by preventing IM and both types of recurrences respectively. Immunotherapy that inhibits immune checkpoint interaction may be an optimal choice for both MO-and IM-HCC. In the future, effective personalized therapy against multifocal HCC may be achieved.