Association of severity in the grading of microvascular invasion with long-term oncological prognosis after liver resection for early-stage hepatocellular carcinoma: a multicenter retrospective cohort study from a hepatitis B virus-endemic area

Background: The presence of microvascular invasion (MVI) is a significant malignant pathological feature related to recurrence and survival after liver resection for hepatocellular carcinoma (HCC). This study aimed to investigate the relationship between the severity in the grading of MVI and long-term oncological outcomes in patients with early-stage HCC.Methods: A retrospective study was conducted on a prospectively maintained multicenter database on patients who underwent curative resection for Barcelona Clinic Liver Cancer stage 0/A HCC between 2017 and 2020. Patients were classified into three groups according to the severity in the grading of MVI: M0 (no MVI), M1 (1-5 sites of MVI occurring =1 cm away from the tumor), and M2 (> 5 sites occurring =1 cm and/or any site occurring > 1 cm away from the tumor). Recurrence-free survival (RFS) and overall survival (OS) were compared among the groups.Results: Of 388 patients, M0, M1, and M2 of the MVI gradings were present in 223 (57.5%), 118 (30.4%), and 47 (12.1%) patients, respectively. The median OS and RFS in patients with M0, M1, and M2 were 61.1, 52.7, and 27.4 months; and 43.0, 29.1, and 13.1 months (both P < 0.001), respectively. Multivariable analyses identified both M1 and M2 to be independent risk factors for OS [hazard ratio (HR): 1.682, P =0.003; and HR: 3.570, P < 0.001] and RFS (HR: 1.550, P =0.037; and HR: 2.256, P < 0.001).Conclusion: The severity in the grading of MVI was independently associated with recurrence and survival after HCC resection. Patients with the presence of MVI, especially those with a more severe MVI grading (M2), require more stringent recurrence surveillance and/or active adjuvant therapy against recurrence.