Clinical significance of microscopic tumor venous invasion in patients with resectable hepatocellular carcinoma

Background. Tumor venous invasion in patients with resectable hepatocellular carcinoma (HCC) is frequent and can be macroscopic and microscopic or microscopic alone. Although macroscopic invasion is a well-established prognostic indicator the clinical significance of microscopic invasion remains unclear. Methods. There were 322 patients enrolled who had undergone curative resection for HCC. The clinico-pathologic factors and prognostic significance associated with macroscopic and microscopic venous invasion were analyzed. Results. Macroscopic invasion was observed in 50 patients (15.5%) and microscopic invasion in 190 (53.0%). The larger the tumor; the more the incidence of venous invasion. There were 140 patients with microscopic invasion only (Croup I). Patients with macroscopic invasion (Group 2, n = 50) also had microscopic invasion. Compared with patients without venous invasion (Croup 3, n = 132), Group 1 had a higher alpha-fetoprotein level, a larger tumor size, and more tumors without encapsulation. For group 1, the 1-, 3-, and 5-year disease-free survival rates were 65.6%, 41.6%, and 30.8%, respectively. The 1-, 3; and 5-year overall survival rates were 87.8%, 60.0%, and 52.7%, respectively. The survival rates of group 1 were lower than those of group and higher than those of group 2 (P < .05). Multivariate analysis indicated that microscopic and macroscopic venous invasion, surgical margin, indocyanine-green retention, and tumor size anti number were significant predictors of postresectional survival. Conclusions. In HCC patients, microscopic venous invasion is frequent and related independently to postresectional outcome.