Clinical Outcomes of Radiofrequency Ablation for Early Hypovascular HCC: A Multicenter Retrospective Study.

Purpose To retrospectively evaluate the clinical outcomes of radiofrequency ablation (RFA) for early hypovascular hepatocellular carcinomas (HCCs) and to compare them with those of typical hypervascular HCCs. Materials and Methods This retrospective multicenter study received institutional review board approval, with a waiver of the need to obtain informed consent. A total of 56 patients (male-to-female ratio, 40:16; mean age, 61.8 years; age range, 33-87 years) with pathologically proven early HCCs that did not meet the noninvasive diagnosis criteria and who were initially treated with RFA at one of five university-affiliated hospitals between January 2009 and December 2013 comprised the study group. Thereafter, 240 patients with hypervascular HCCs initially treated with RFA in the same period in a historical cohort were selected as control patients. Overall survival (OS), progression-free survival (PFS), and cumulative incidence of local tumor progression (LTP) were estimated by using Kaplan-Meier analysis and were compared by using the Cox proportional hazard regression model. After the first analysis, propensity score analysis was performed to reduce potential bias. Results Complete ablation was achieved in all 56 patients with early hypovascular HCCs after RFA. The estimated 5-year cumulative incidence of LTP in the 56 patients with early hypovascular HCCs was significantly lower than in the 240 patients with hypervascular HCCs (5.4% for early hypovascular HCCs vs 20.8% for hypervascular HCCs; hazard ratio = 6.57 [95% confidence interval: 1.59, 27.2]; P = .009). After propensity matching, the estimated 5-year cumulative incidence of LTP in patients with early hypovascular HCCs was still significantly lower than that in patients with hypervascular HCCs (5.4% vs 23.0%; P = .025; hazard ratio = 5.71 [95% confidence interval: 1.27, 25.8]). OS was not significantly different between the groups (P = .100). One-year PFS in the 56 patients with early hypovascular HCCs, on the other hand, appeared to be favorable at 92.7%, compared with 79.4% in the 240 patients with hypervascular HCCs, but overall, PFS was not significantly different (P = .066). Conclusion RFA of early hypovascular HCCs provided similar OS and PFS compared with RFA of typical hypervascular HCCs, despite its significantly lower 5-year cumulative incidence of LTP. RSNA, 2017 Online supplemental material is available for this article.