Evaluation of the Efficacy and Toxicity of Radiotherapy for Type III-IV Portal Vein Tumor Thrombi

Background: Type Ⅲ and Ⅳ portal vein tumor thrombi (PVTT) cannot be removed through surgery, and no effective therapeutic procedure is available. Type Ⅲ/Ⅳ PVTT can be downstage to type I/II PVTT by using Radiotherapy, and can further be can be removed surgically. Thus, radiotherapy may be an effective treatment for type Ⅲ/Ⅳ PVTT. This study aims to evaluate the efficacy and toxicity of radiotherapy for type III-IV PVTT. Methods: This prospective study was conducted from August 1, 2017, to September 30, 2019, for patients with type Ⅲ and Ⅳ PVTT. Patients received radiotherapy with a target dose of 50Gy/25f or 59.5Gy/17 f. Advanced radiological technique such as image fusion technique for CT image and MRI image were utilized to produce more precise lesion localization, and limit the dose to organs at risk in order to get a better downstage rate and less adverse complications. Results: Nine (9) patients with type Ⅲ PVTT and 5 patients with type Ⅳ PVTT were included in this study. 12 patients received a radiotherapy dose of 50Gy/25f, 2 patients received 59.50Gy/17 f. After radiotherapy, 92.9% of patients with PVTT were successfully downstage to type II/I. In patients with primary hepatocellular carcinoma, 8 patients (accounting 88.9%) achieved down-stage. 5 patients with other types of tumors achieved downstage which accounts 100%. In addition, none of the 14 patients observed radiation hepatitis and radiation liver failure. And none of the patients developed gastrointestinal ulcers and thrombocytopenia. Conclusion: Radiotherapy is a suitable treatment measure for type Ⅲ and Ⅳ PVTT to get downstage and make the opportunity for surgery. Image fusion technology for precise lesion location such as CT-MRI image fusion, and strict dose limitation of organ at risk, contributed to the improvement of radiotherapy efficiency and the significant decrease in adverse complications.