Long-term results of microwave ablation in the treatment of early-stage HCC

Background and aims: Microwave ablation plays a pivotal role in the treatment of very-early and early-stage HCC. The aim of the this study was to evaluate objective response rate (ORR) and local tumor progression (LTP) rate in patients with very-early and early-stage HCC treated with microwave ablation. Approach and results: The current study is a single-center, single-arm and retrospective study that included all eligible consecutive patients with very-early and early-stage HCC treated with microwave ablation between 2016 and 2023. Eligibility criteria included: solitary nodules with a diameter ≤ 3 cm or up to 3 nodules with sizes ≤ 3 cm (BCLC 0-A); absence of vascular invasion and extrahepatic disease; good performance status (ECOG 0-1); preserved liver function (Child-Pugh A-B, ALBI grade 1-2). Exclusion criteria included: combined treatment with intra-arterial therapies (e.g., MWA+TACE); treatment of local recurrences from previous non-ablative locoregional treatments (e.g., TACE, TARE). Primary endpoints were ORR and LTP based on modified Response Evaluation Criteria in Solid Tumors, as evaluated by blinded, independent, central review. Secondary endpoint included overall survival (OS) and the evaluation of morphologic data (size, location, distance for vessels > 3mm), technical data (MW power, released energy) and clinical data (AFP) as possible predictive factor for LTP. 516 nodules in 379 patients who underwent MW ablation were evaluated. 278 HCC nodules (mean size: 17mm) in 207 patients (mean age: 70) were included. Mean follow-up time was 36.2 months (range: 1 – 104 months). ORR at 1 month was 94.2. Median time for LTP detection was 20.1 months. 1-year, 3-year, 5-year and 7-year OS were respectively 97,2%, 82,7%, 69,4%, 60,1%. 1-year, 3-year, 5-year and 7-year LTP cumulative incidence were respectively 5.1, 14.4, 16.5 and 17.6. 1-year, 3-year, 5-year and 7-year LTP-free survival were respectively 88.4, 72.5, 64.2 and 55.7. According to univariate and multivariate analyses, tumor size > 2 cm (OR=1.626; 95% CI, 1.002-2.650; p=.02) and distance from a blood vessel sizing > 3 mm (OR=0.754; 95% CI, 0.611.0.932; p<.01) were significant predictive factors of LTP after MWA. Conclusions: In the study, microwave ablation proved meaningful response rates and prolonged duration of response in the treatment of very-early and early-stage HCC.