Role of Stereotactic Body Radiation Therapy in Portal Vein Tumor Thrombosis in Hepatocellular Carcinoma: A Prospective Single Institute Experience

Abstract

Patients diagnosed with Hepatocellular carcinoma (HCC) complicated with portal vein tumor thrombosis (PVTT) have a limited number of treatment options available and are associated with an overall poor prognosis. With the recent developments in the field of radiation therapy, the role of radiotherapy particularly Stereotactic Body radiotherapy (SBRT) has increased as a loco-regional therapy for HCC. This study was planned to evaluate the role of SBRT in Locally advanced HCC complicated with PVTT and its role as loco-regional therapy. We conducted a prospective study that included patients diagnosed with HCC complicated with PVTT Child-Turcotte Pugh (CTP) Class A/B with a maximum score of 7, diagnosed on triple phase Contrast-Enhanced - MRI unsuitable for other ablative procedures. Patients with Bilirubin levels > 4 mg/dl, active Hepatitis, CTP score >7, normal liver volume <700cc or history of prior radiotherapy were excluded from the study. Patients underwent a contrast enhanced 4D-CT simulation with abdominal compression and were planned for SBRT using VMAT technique. Patients were followed-up as per Institute protocol. CECT or MRI for a radiological response was done for response assessment using mRECIST criteria version 1.1. A baseline MRI was done at one-month post-SBRT to understand any RT changes in the liver and to differentiate from tumor progression during the response assessment at three months. A total of 22 patients with HCC were recruited and received SBRT to PVTT, with a dosage between 30-42 Gy over 6 fractions treated on alternate days. Patients were assessed post-treatment with triphasic CE-MRI every 3 months as per institute protocol. Five patients had achieved Complete response in form of Portal vein recanalization. Three patients had Partial response to the treatment. Seven patients maintained stable disease status whereas six patients had disease progression during the entire course of treatment. The response rate (CR+PR) to treatment was 36.3% at the time of analysis. The Overall Response rate (CR+PR+SD) was 69%. No grade 3 or 4 toxicities were observed and treatment was tolerated well by patients. Kaplan-Meier method was applied to calculate the survival probability at various follow-up intervals. The median time for overall survival was 25 months ((95% CI: 15-35). Out of the 22 subjects included in the study, 6 patients died. There was a 78% survival probability at 12 months and a 68% survival probability at 18 months of follow-up. This prospective single-arm study demonstrated the vital role of SBRT in the treatment of Hepatocellular carcinoma with Portal vein tumor thrombosis and its efficacy in terms of achieving excellent local control with relatively lesser toxicities compared with existing treatment modalities. Patients have shown benefit post-treatment in terms of thrombus reduction and restoration of Portal vein flow making them suitable for further treatment like Resection or TACE.