Stereotactic body radiotherapy versus intensity-modulated radiotherapy for hepatocellular carcinoma with portal vein tumor thrombosis

Background: It is unclear whether robotic stereotactic body radiotherapy (SBRT) is superior to intensity-modulated radiotherapy (IMRT) in advanced hepatocellular carcinoma (HCC). This study aimed to compare the long-term outcomes of SBRT with those of IMRT in HCCs with portal vein tumor thrombosis (PVTT). Methods: We retrospectively evaluated 287 HCC patients with PVTT who underwent radiotherapy between January 2000 and January 2017. Of them, 154 and 133 patients were treated with IMRT and SBRT, respectively. Overall survival (OS), progression-free survival (PFS), intrahepatic control (IC), and local control (LC) were evaluated in univariable and propensity-score matched analyses. Results: After matching, 102 well-paired patients were selected. There was no significant difference in the 6-, 12-, 24-, and 60-month cumulative OS (73.5, 42.9, 23.6, 7.6% vs. 72.4, 45.1, 29.8, 13.2%, P=0.151), PFS (53.9, 29.3, 21.8, 7.5% vs. 54.5, 19.3, 12.0, 9.6%, P=0.744) , IC (61.4, 45.7, 39.0, 26.8% vs. 75.1, 45.8, 35.9, 28.7%, P=0.144), and LC (85.2, 56.5, 52.1, 47.4% vs. 87.4, 65.2, 62.1, 62.1%, P=0.191) between the IMRT and SBRT groups. A biologically effective dose assumed at an a/b ratio of 10 (BED10) of ≥100 Gy was the optimal cutoff for predicting the OS, PFS, IC, and LC in the patients who received SBRT. Conclusions: When high-precision tracking technology is available, SBRT appears to be a safe and more time-efficient treatment, achieving comparable OS, PFS, IC and LC to IMRT for local advanced HCC with PVTT. A BED10≥100 Gy is recommended if tolerated by normal tissue.