Grading severity of microscopic vascular invasion was independently associated with recurrence and survival following hepatectomy for solitary hepatocellular carcinoma

Background: Hepatectomy is the preferred treatment for solitary hepatocellular carcinoma (HCC) without macrovascular invasion and distant metastasis, but long-term survival remains unsatisfactory in certain patients. We sought to identify whether the grading severity of microscopic vascular invasion (MVI) was associated with recurrence and survival among patients with solitary HCC.Methods: Consecutive patients who underwent hepatectomy for solitary HCC were identified from a multicenter prospectively-collected database. Patients were categorized into three groups according to the MVI grading system proposed by the Liver Cancer Pathology Group of China: M0 (no MVI), M1 (1-5 sites of MVI occurring < 1.0 cm away from the tumor), and M2 (> 5 sites occurring <= 1.0 cm or any site occurring > 1 cm away from the tumor). Recurrence-free survival (RFS) and overall survival (OS) were compared among the groups.Results: Among 227 patients, 97 (57.4%), 83 (30.4%), and 47 (12.1%) patients had M0, M1, and M2, respectively. Median RFS rates among patients with M0, M1, and M2 were 38.3, 35.1, 11.6 months, respectively, while OS rates were 66.8, 62.3, 30.6 months, respectively (both P < 0.001). Multivariate Cox regression analyses demonstrated that both M1 and M2 were independent risk factors for RFS (hazard ratio 1.20, 95% CI: 1.03-1.89, P=0.040; and 1.67, 1.06-2.64, P=0.027) and OS (1.28, 1.05-2.07, P=0.035; and 1.97, 1.15-3.38, P=0.013).Conclusions: Grading severity of MVI was independently associated with RFS and OS after hepatectomy for solitary HCC. Enhanced surveillance for recurrence and potentially adjuvant therapy may be considered for patients with MVI, especially individuals with more severe MVI grading (M2).