Tumor size larger than 6.5 cm and microvascular invasion are comparable prognosticators for hepatocellular carcinoma: a multi-institutional observational study.

[BACKGROUND] Recent study showed that T1 hepatocellular carcinoma (HCC) > 6.5 cm had survivals comparable to T2 tumors. Nevertheless, the differential impact between tumor size > 6.5 cm and microvascular invasion (mVI) on survival of HCC was rarely discussed. The current study aimed to compare the specific impact of tumor size > 6.5 cm and mVI on the survival outcome of HCC after liver resections.

[METHODS] Operated HCC patients were identified from the Chang Gung Research Database (CGRD), and the patients with T1bN0M0 or pT2N0M0 tumors were enrolled. The survivals of patients with either tumor size > 6.5 cm, mVI, or multiple tumors were compared.

[RESULTS] From 2002 to 2018, a total of 3449 patients who underwent surgery for T1bN0M0 or T2N0M0 HCC were identified from the CGRD. After excluding cases who died within 30 days of surgery (n = 31), Kaplan-Meier survival analysis discovered that tumor > 6.5 cm without mVI had survivals similar to those of solitary tumor > 2 cm with mVI. Cox regression multivariate analysis further demonstrated that tumor size > 6.5 cm and mVI were independent poor prognostic factors for both mortality and tumor recurrence after surgery. Subgroup analysis further discovered that the presence of both tumor size > 6.5 cm and mVI substantially compromised survivals after liver resection.

[CONCLUSION] Our study demonstrated that tumor size larger than 6.5 cm and mVI are comparable prognosticators for HCC. In addition, the presence of these two adverse factors significantly worsens HCC survival outcomes compared to the presence of either factor alone. Further studies are warranted to validate our findings.