552 - Percutaneous Radiofrequency Ablation of Perivascular versus Nonperivascular Hepatocellular Carcinomas ≤ 3 Cm: An Inverse Probability of Treatment Weighting Analysis

Purpose: To compare long-term outcomes of percutaneous radiofrequency ablation (RFA) between perivascular and nonperivascular hepatocellular carcinomas (HCCs) ≤ 3 cm using inverse probability of treatment weighting (IPTW).

Materials and Methods: This retrospective study included 650 treatment-naive patients with a single small (≤ 3 cm) HCC treated with RFA between January 2005 and December 2020. Tumors were categorized as perivascular or nonperivascular based on proximity to large vessels. IPTW based on propensity scores was applied to balance baseline covariates between the groups. Local tumor progression (LTP) was evaluated using competing risks regression and Fine–Gray models. Overall survival (OS) was assessed using IPTW-adjusted Cox proportional hazards models.


Results: After IPTW adjustment, both groups showed balanced baseline characteristics. The 5-year LTP rate was significantly higher in the perivascular group (28.6%) compared with the nonperivascular group (12.9%) (p < .001). The 15-year OS rate was lower in the perivascular group (35.0%) than in the nonperivascular group (51.8%) (p = .011). Major adverse events occurred infrequently and were not significantly different between the groups (1.6% vs. 0.9%, p = .328).

Conclusion: Perivascular tumor location is associated with higher recurrence and lower survival following RFA for small HCCs compared to nonperivascular tumors. These findings underscore the need for careful treatment planning and consideration of adjunctive strategies in patients with perivascular HCC