Efficacy of Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma by Underlying Liver Disease Etiology

Abstract

<h3>Purpose/Objective(s)</h3> The use of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) has been steadily increasing. Recently, it was reported that patients with HCC have a differential response to immune-checkpoint inhibitor based on the background liver disease etiology. Whether outcomes of SBRT are affected by underlying liver disease etiology is currently unknown. We therefore reviewed outcomes of SBRT with special focus on tumor size, BED, and underlying liver disease etiology. <h3>Materials/Methods</h3> This study is a retrospective review of HCC patients treated with SBRT at one institution between 2009 and 2021. Patients with tumor thrombus or extrahepatic disease were excluded. Kaplan-Meier curves and Cox regression models were used to describe freedom from local progression (FFLP) and overall survival (OS) rates and examine potential prognostic factors. <h3>Results</h3> One-hundred and sixty-four patients met study entry criteria. Median gross tumor volume (GTV) size was 9.3 cc (range 0.3 to 762.4 cc). 67% of patients had a history of hepatitis C, and 9% had a history of hepatitis B. 71% of patients received our institutional standard SBRT dose of 50 Gy in 5 fractions (biological effective dose [BED] 100 Gy). Other patients received lower doses ranging from 30 to 47.5 Gy in three to five fractions (BED range 48 to 93 Gy) if necessary to preserve normal liver tissue. Median follow-up time was 43 months (interquartile range [IQR] 36 to 52 months). Seventeen in-field failures and 67 deaths have occurred. 3- and 5-year FFLP rates were 84% and 75%, and 3- and 5-year OS rates were 65% and 48%, respectively. History of hepatitis C was associated with better FFLP (HR=0.36 (95% CI:0.14, 0.94), p=0.038). Treatment with 50 Gy was associated with better FFLP compared to treatment with lower doses for patients with hepatitis C (HR=0.15 (95%CI: 0.04, 0.63), p=0.01) but not for other patients (HR=3.1 (95%CI: 0.38, 24.7), p=0.29). <h3>Conclusion</h3> SBRT for HCC yields excellent local control, particularly for patients with hepatitis C. In hepatitis C patients, dose escalation beyond a BED of 100Gy may be more important for local control than in non-hepatitis C patients. More studies are necessary to better understand if HCC etiology should be considered when planning SBRT.