3:27 PM Abstract No. 174 A retrospective comparison of ablation volumes, clinical response, and outcomes of overlapping versus simultaneous microwave ablation in patients with hepatocellular carcinoma

Abstract

To compare the ablation volumes, clinical response, and outcomes after microwave ablation (MVA) with overlapping ablations (OA) vs. simultaneous ablations (SA) in patients with hepatocellular carcinoma (HCC). This retrospective study included 45 patients with 45 HCC who underwent MVA between 2013 and 2017. MVA was performed sequentially with one antenna in the OA group (n = 33; 23 M, 10 F; mean age: 61.9 y ± 9) and simultaneously with two antennae in the SA group (n = 12; 10 M, 2 F; mean age: 62.2 y ± 8.7). Patients were followed with CT or MR imaging for at least a year to identify tumor progression. Clinical and technical factors were reviewed. Ablation length, diameter, and volumes on first follow-up cross-sectional imaging were calculated. Tumor response, including complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) were evaluated according to mRECIST. Local tumor progression (LTP), time to progression (TTP), progression-free survival (PFS), and overall survival (OS) were compared between groups. There were no significant differences between both groups in terms of tumor etiology, MELD, ECOG, Child-Pugh, BCLC scores, and median tumor size (OA: 2.45 cm; SA: 3 cm). The median wattage for OA and SA groups was not significantly different (66.8 W ± 16.7 vs. 58.3 W ± 11.6). Mean ablation time was longer in the OA group compared to the SA group (16.1 min ± 4.8 vs. 9.1 min ± 2.0, p<0.0001). Mean ablation volumes were larger in the SA group compared to the OA group (62.7 cm3 ± 20.9 vs. 36.2 cm3 ± 39.7, p<0.0001). There were no significant differences between OA and SA groups in terms of CR, PR, SD, or PD on follow-up imaging, as well as clinical outcomes, including LTP (median: 5 vs. 6.5 mo), TTP (median: 5 vs. 4 mo), and PFS (median: 13 vs. 17 mo). Overall survival was similar between groups at 12 mo (90.9% vs. 91.7%), but showed a decreased trend for the OA group at 24 mo (50% vs. 88.9%). SA leads to larger ablation volumes and shorter ablation times in patients with HCC but is not associated with improved clinical response, LTP, TTP, PFS, or OS when compared to patients undergoing OA.