Abstracts
2001 Digestive Disease Week

# 483 Predictors of Microvascular Invasion in Patients with Hepatocellular Carcinoma Who Are Candidates for Orthotopic Liver Transplanation.
Nestor F. Esnaola, Gregory Y. Lauwers, Nadeem Q. Mirza, David M. Nagorney, Dorota A. Doherty, Iwao Ikai, Jacques Belghiti, Yoshio Yamaoka, Steven A. Curley, Lee M. Ellis, J. Nicolas Vauthey, Houston, TX, Boston, MA, Rochester, MN, Kyoto, Japan, Paris, France

BACKGROUND: Vascular invasion is a major determinant of outcome after orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC). While imaging techniques can often detect major vascular invasion, microvascular invasion (MVI) cannot be assessed prior to transplantation. The purpose of this study was to identify preoperative predictors of MVI in patients with HCC who are candidates for OLT.

METHODS: A cohort of 245 patients who underwent hepatic resection for HCC and fulfilled the criteria for OLT (i.e. single tumors £ 5 cm or £ 3 multiple tumors £ 3 cm ) were identified from a multi-institutional database. Patients with fibrolamellar HCC, positive lymph nodes, and major vascular invasion were excluded. Univariate and multivariate predictors of MVI were identified.

RESULTS: The median age was 62 (range 28-81), and 71% of the patients were male. 85% of the patients had single tumors, and the median tumor size was 3.0 cm (range 0.8-5.0). Overall, 32% of the patients had evidence of MVI on pathologic analysis. Increasing tumor number and size were associated with MVI. 29.1% of the patients with single tumors had evidence of MVI, compared to 47.2% of patients with multiple tumors (p=0.03). Only 24.6% of patients with tumors £ 2 cm had evidence of MVI, compared to 30.8% and 46.5% of patients with tumors > 2-4 cm and > 4 cm, respectively (p=0.05). Tumor grade was highly correlated with MVI: 12.5% of patients with well differentiated tumors had MVI, compared to 28.7% and 48.8% of patients with moderately and poorly differentiated tumors, respectively (p<0.001). There was no association between age, sex, hepatitis B serology, Child class, preoperative alphafetoprotein level, hepatitis/fibrosis grade and MVI. Univariate predictors of MVI were entered into a stepwise logistic regression model. The independent predictors of MVI were tumor size > 4cm (odds ratio [OR], 2.3 [95% confidence interval (CI), 1.1-4.9]) and high tumor grade (OR, 6.1 [95% CI, 2.0-19.3]).

CONCLUSIONS: Tumor size and grade are strong predictors of microvascular invasion. A tumor biopsy with pathological grading performed at the time of pretransplantation ablative therapy could improve the selection of patients with hepatocellular carcinoma who are candidates for orthotopic liver transplantation.