Tumor shrinkage after simultaneous proton therapy for multiple hepatocellular carcinomas

Area of Science:

• Oncology
• Radiation Oncology
• Hepatology

Background:

• Hepatocellular carcinoma (HCC) is a common primary liver cancer.
• Multiple HCCs present unique treatment challenges.
• Simultaneous radiotherapy for multiple HCCs is not well-reported regarding tumor shrinkage.

Purpose of the Study:

• To investigate tumor shrinkage and treatment outcomes in patients with multiple HCCs treated with simultaneous proton beam therapy (PBT).
• To explore the relationship between radiation dose and tumor response in multifocal HCC.

Main Methods:

• Retrospective analysis of 46 patients with 95 HCC lesions treated with PBT between 2008 and 2018.
• Kaplan-Meier method used to determine overall survival (OS), local control (LC), and response rates (CR+PR).
• Analysis of different PBT combination protocols (A, B, C) and their impact on lesion shrinkage.

Main Results:

• The 3-year OS rate was 50.3%, with a 3-year LC rate of 90.4% and CR+PR rate of 85.2% for all lesions.
• No significant difference in 1-year CR+PR rates was observed between PBT protocols A and B (75.8% vs. 56.4%, P=0.14) or A and C (62.5% vs. 57.1%, P=0.35).
• Individual lesions within the same patient showed variable shrinkage despite different PBT protocols, indicating no clear dose-response relationship for shrinkage.

Conclusions:

• Simultaneous PBT can achieve high local control and response rates for multiple HCCs.
• Tumor shrinkage can vary among multiple HCCs treated concurrently, even with different radiation doses.
• There is no significant relationship identified between radiation dose and tumor shrinkage in this cohort of multiple HCCs treated with PBT.