Factors correlated with portal venous invasion by hepatocellular carcinoma: univariate and multivariate analyses of 232 resected cases without preoperative treatments.

The postoperative intrahepatic recurrence of hepatocellular carcinoma (HCC) is high. It is difficult to distinguish whether the recurrence is metastatic or new primary lesion. To determine the malignant potential of HCC itself, we analyzed the risk factors associated with portal venous invasion since this is direct evidence of tumor invasiveness. Two hundred and thirty-two patients who underwent curative hepatectomy for HCC without preoperative treatments were included in this study, because preoperative treatment caused the tumor to undergo a variety of histologic change. We analyzed the risk factors linked to portal venous invasion by both univariate and multivariate analyses. In an univariate analysis, tumors larger than 3 cm, high histologic grade (III or IV), the presence of fibrous capsule, necrosis, mitotic rate of more than 4/10 high power fields, peliotic change, presence of tumor giant cells, high platelet count, low level of indocyanine green retention rate at 15 minutes, and the absence of cirrhosis were significantly correlated with portal venous invasion. In multiple stepwise logistic regression analysis, tumors larger than 3 cm, high histologic grades, and the presence of fibrous capsule were strong predictors of portal venous invasion by HCC. Because the blood vessels of the fibrous capsule were frequently invaded by cancer cells, it may have been possible to prevent postoperative metastatic recurrence if HCC were resected before becoming large enough to have a fibrous capsule.