Hepatic resection for hepatocellular carcinoma based on tumor hemodynamics.

Survival or disease-free survival is not considered an appropriate surrogate outcome for the locoregional curability (i.e. surgical margin) of hepatectomy for hepatocellular carcinoma because these are greatly influenced by non-metastatic factors like multicentric carcinogenesis (MC) or liver function. Hepatocellular carcinoma metastasizes by hematogenous seeding; therefore, the tumor blood flow (TBF) drainage area is a high-risk area for intrahepatic metastasis, and can be identified by computed tomography under hepatic arteriography and completely resected as part of the surgical margin. The TBF pattern is classified into marginal, portal vein or hypovascular types. Partial hepatectomies were mostly performed in patients with marginal or hypovascular type, whereas anatomical surgery was frequently performed in those with portal vein type. Pathologically, nodules inside the TBF drainage area were moderately or poorly differentiated carcinomas, suggesting intrahepatic metastasis. In contrast, those outside the drainage area were frequently solitary and contained well-differentiated carcinoma, which is consistent with MC. The pattern of tumor recurrences after TBF-based hepatectomy is divided into two distinct groups - "a few nodules" and "many nodules in multiple segments or extrahepatic" - indicating that intrahepatic recurrences develop from MC and from circulating tumor cells in peripheral blood, respectively. Anatomical resection has not shown a survival benefit over that of TBF-based partial hepatectomy. TBF-based hepatectomy enables us to preserve liver function without compromising locoregional curability.