MRI-guided radiotherapy for PVTT in HCC patients: evaluation of the efficacy and safety

Abstract

Purpose: This study aims to evaluate the efficacy, feasibility, and safety of the magnetic resonance imaging (MRI)-guided tumor tracking hypofractionated radiotherapy (HFRT) and stereotactic body radiation therapy (SBRT) for portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) patients.

Methods: We retrospectively reviewed the twelve cases of unresectable HCC with tumor thrombus in the main trunk or first branch of the portal vein that were treated with MRI-guided tumor tracking HFRT or SBRT using the ViewRay Linac MRIdian system between June 2019 and January 2021. The HFRT was performed with a total of 50 Gy in 10 fractions, and SBRT performed in a range of 36-50 Gy with 4-5 fractions. The median biologic effective dose (BED) with an a/b ratio of 10 was 75 Gy₁₀ (range 68.4-100 Gy₁₀).

Results: The median follow-up duration was 5.0 months (range 1.9-12.8 months). Ten patients (83.3%) showed an objective response of PVTT. At the time of analysis, ten patients (83.3%) showed local control. The 1-year intrahepatic control rate was 48.9%. Three patients (25%) showed mild gastrointestinal symptoms, and there were no cases of grade 3 or higher toxicity. For hepatic toxicity, there were no cases in which the Child-Pugh score increased by more than two points after RT without disease progression.

Conclusion: MRI-guided tumor tracking HFRT and SBRT was a feasible, effective, and safe treatment option in HCC patients with tumor thrombi in the main trunk or first branch of the portal vein.

Keywords: Hepatocellular carcinoma; Hypofractionated radiotherapy; MRI-guided radiotherapy; Portal vein tumor thrombus; Stereotactic body radiation therapy.