Predictors of microvascular invasion in patients with hepatocellular carcinoma who are candidates for orthotopic liver transplantation

Microvascular invasion affects survival after orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC). We sought to identify preoperative predictors of microvascular invasion in patients with HCC who were candidates for OLT. A cohort of 245 patients who underwent resection for HCC and fulfilled the criteria for OLT (i.e., single tumors : 5 cm or no more than three tumors less than or equal to3 cm) were identified from a multi-institutional database. Thirty-three percent of the patients had pathologic evidence of microvascular invasion. Thirty percent of patients with single tumors and 47% with multiple tumors had microvascular invasion (P = 0.04). Only 25% of patients with tumors smaller than less than or equal to2 cm had microvascular invasion, compared to 31% and 50% with tumors greater than 2 to 4 cm or larger than 4 cm, respectively (P = 0.01). Tumor grade was highly correlated with microvascular invasion: 12% of patients with well-differentiated tumors had microvascular invasion, compared to 29% and 50% with moderately or poorly differentiated tumors, respectively (P < 0.001). The independent predictors of microvascular invasion were tumor size greater than 4 cm (odds ratio [OR], 3.0, 95% confidence interval [0], 1.2 to 7.1), and high tumor grade (OR, 6.3; 95% CI, 2.0 to 19.9). Tumor size and grade are strong predictors of microvascular invasion. A tumor biopsy with pathologic grading at the time of pretransplantation ablative therapy could improve selection of patients with HCC for OLT.