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

Background. Tumor venous invasion in patients with resectable hepatocellula r carcinoma (HCC) is frequent and can be macroscopic and microscopic or mic roscopic alone. Although macroscopic invasion is a well-established prognos tic indicator the clinical significance of microscopic invasion remains unc lear. Methods. There were 322 patients enrolled who had undergone curative resect ion for HCC. The clinico-pathologic factors and prognostic significance ass ociated with macroscopic and microscopic venous invasion were analyzed. Results. Macroscopic invasion was observed in 50 patients (15.5%) and micro scopic invasion in 190 (53.0%). The larger the tumor; the more the incidenc e of venous invasion. There were 140 patients with microscopic invasion onl y (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%, respectivel y. 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 gro up and higher than those of group 2 (P < .05). Multivariate analysis indica ted that microscopic and macroscopic venous invasion, surgical margin, indo cyanine-green retention, and tumor size anti number were significant predic tors of postresectional survival. Conclusions. In HCC patients, microscopic venous invasion is frequent and r elated independently to postresectional outcome.