A retrospective study assessing the efficacy of combined transarterial chemoembolization and microwave ablation in the treatment of large, unresectable hepatocellular carcinoma (≥5 cm).

Abstract

e16274 Background: Unresectable large hepatocellular carcinoma (HCC) ≥5 cm without vascular invasion or extrahepatic metastasis, transarterial chemoembolization (TACE) is local treatment, though its efficacy is limited. Ablation can significantly enhance outcomes as a crucial adjunct. Based on mRECIST and RECICL criteria, this study aims to evaluates the efficacy of adjuvant Tislelizumab following TACE and MWA(T+M) for HCC ≥5 cm without vascular invasion or extrahepatic metastasis. Methods: This retrospective multicenter study screened large hepatocellular carcinoma (HCC) received initial transarterial chemoembolization (TACE) and microwave ablation (MWA). Inclusion criteria included imaging or histologically confirmed HCC, tumor size ≥5 cm, no vascular invasion or extrahepatic metastasis, no prior antitumor therapy, and complete response (CR) after 1–3 TACE and 1–2 MWA treatments.The primary endpoints were progression-free survival (PFS) based on mRECIST and RECICL (version 6) criteria. Secondary endpoints encompass overall survival (OS). Results: A total of 46 patients treated at our institution from June 2018 to November 2023 were included in the study, with 20 cases of hepatitis B, 20 cases of hepatitis C, and 6 cases without hepatitis.All were BCLC stages A/B, with average tumor size of 6.5 cm. 65.2% (30/46) surpassed the UP TO 7 criteria. Fourteen patients received adjuvant therapy postoperatively, with an average treatment duration of 10 months.The median follow-up time was 56.5 months (95%CI: 33.1–79.9 months), with a median overall survival (OS) of 56.1 months. Median progression-free survival (PFS) was 17.5 months (mRECIST) and 55.1 months (RECICL). The Cox regression model identified α-fetoprotein (AFP) <400 ng/ml and ALBI grade I as independent favorable prognostic factors (P = 0.021, P = 0.024).Hepatitis type did not significantly impact outcomes or prognosis. Subgroup analysis of median progression-free survival (mPFS) for the non-adjuvant (T+M) and post-operative adjuvant treatment (T+M+I) groups is shown in the table below. Non-parametric analysis indicated that RECICL criteria more accurately reflected true overall survival (OS) compared to mRECIST (P < 0.001). Conclusions: TACE combined with MWA represents a viable treatment approach for HCC ≥ 5 cm. Adjuvant Tislelizumab showed potential for improving PFS. RECICL criteria may be more suitable for evaluating efficacy in early-to-intermediate stage HCC undergoing local interventional treatments. Progression-free survival (PFS) based on different tumor responses. PFS mRECIST RECICL Tislelizumab With Without With Without Median, months 23.4 (95% CI: 13.8–32.9) 17.5 (95% CI: 13.8–21.2) 62.8(95% CI: 26.2–99.5) 42.9 (95% CI: 11.9–74.3) 1-year, % 91.7 61.5 95.7 81.3 3-year, % 30.6 20.4 68.3 52.0 5-year, % NR 10.2 54.6 34.7