Oncologic Outcomes After ABO-Incompatible Versus Compatible Living Donor Liver Transplantation for Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Background: ABO-incompatible living-donor liver transplantation (ABOi LDLT) can expand the donor pool for patients with hepatocellular carcinoma (HCC), but concerns remain regarding tumor recurrence and long-term survival. Methods: A systematic review and meta-analysis was performed according to PRISMA 2020. PubMed, Embase, and Web of Science were searched. Comparative studies evaluating oncologic outcomes after ABOi versus ABO-compatible (ABOc) LDLT for HCC were included in the quantitative synthesis; non-comparative studies were included in the qualitative synthesis. Hazard ratios (HRs) for recurrence-free survival (RFS) and overall survival (OS) were pooled using a random-effects model. When HRs were not directly reported, they were estimated from Kaplan–Meier curves using established methods. Results: Sixteen reports were screened, 12 full-text articles were assessed, and 8 studies were included in the systematic review. Three comparative single-center cohort studies were eligible for meta-analysis. Pooled analysis showed no significant difference between ABOi and ABOc LDLT for RFS (HR 1.07, 95% confidence interval [CI] 0.77–1.49; I2 = 0%) or OS (HR 1.08, 95% CI 0.74–1.57; I2 = 0%). Five additional studies were synthesized qualitatively, suggesting that recurrence risk may be influenced more by tumor biology and peri-transplant management, including desensitization intensity and immunosuppression exposure, than by ABO incompatibility itself. Conclusions: Current limited comparative evidence does not demonstrate inferior RFS or OS after ABOi LDLT in carefully selected patients with HCC. Larger multicenter comparative studies with standardized reporting of tumor biology, desensitization protocols, and immunosuppression exposure are warranted to confirm these findings and clarify protocol-related effects on post-transplant recurrence.