Combination therapy with TACE + ablation versus TACE + SBRT for hepatocellular carcinoma (HCC): Comparative analysis with propensity score-weighted cohorts.

Abstract

443 Background: To assess the relative efficacy and toxicity associated with TACE+Ablation (Ablation) or TACE+SBRT (SBRT) in a large cohort of patients with unresectable HCC. Methods: Patients with HCC undergoing Ablation or SBRT from 2006-2016 with available follow up were included. Treatment groups were different at baseline regarding tumor stage (BCLC A, B and C: 96%, 4%, 0% (Ablation) vs. 73%, 14% and 13% (SBRT), P < 0.001) and severity of liver disease (CTP A, B, and C: 55%, 45% and 0% (Ablation) vs. 50%, 41%, and 9% (SBRT), P = 0.007). Propensity scores were calculated with age, sex, BCLC stage, CTP class, etiology of liver disease, tumor number, and diameter to balance the cohorts. Average treatment effects on survival with multivariable propensity score-weighted competing risk Cox regression models were evaluated, with BCLC stage, number of treated tumors and liver transplant as additionally controlled variables. Primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS), local tumor control and hepatotoxicity. Treatment-related hepatotoxicity was defined as a two point change in CTP within six months after treatment. Results: 192 subjects were included (101 Ablation, 91 SBRT; median age=60 years, 75% men). Liver disease included HCV (78%), alcohol (35%) and NASH (8%). Liver transplant-adjusted 1- and 2-year OS rates were significantly greater for Ablation vs SBRT (88% vs. 75% and 77% vs. 50%, P<0.001). 1-and 2-year PFS rates were significantly greater for Ablation vs. SBRT (84% vs. 65% and 75% vs. 51%, P < 0.001). 1- and 2- year local tumor control rates were similar with both strategies (99% vs. 91% and 94% vs. 87%, P=0.298). Propensity score-weighted multivariable analysis showed significantly higher OS (sHR: 2.31, P = 0.006) and PFS rates (sHR:1.75, P = 0.008) with Ablation compared to SBRT. Ablation was also associated with lower post-treatment hepatotoxicity compared with SBRT (5% vs. 12%, P = 0.001). Conclusions: TACE+Ablation demonstrated higher OS/PFS and lower post-treatment hepatotoxicity compared with TACE+SBRT. Local disease control up to two years was equivocal, potentially suggesting equipoise for bridge to transplant.