Optimal stereotactic body radiotherapy dosage for hepatocellular carcinoma: a multicenter study

Background The optimal dose and fractionation scheme of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) remains unclear due to different tolerated liver volumes and degrees of cirrhosis. In this study, we aimed to verify the dose-survival relationship to optimize dose selection for treatment of HCC. Methods This multicenter retrospective study included 602 patients with HCC, treated with SBRT between January 2011 and March 2017. The SBRT dosage was classified into high dose, moderate dose, and low dose levels: SaRT (BED10 >= 100 Gy), SbRT (EQD(2) > 74 Gy to BED10 < 100 Gy), and ScRT (EQD(2) < 74 Gy). Overall survival (OS), progression-free survival (PFS), local control (LC), and intrahepatic control (IC) were evaluated in univariable and multivariable analyses. Results The median tumor size was 5.6 cm (interquartile range [IQR] 1.1-21.0 cm). The median follow-up time was 50.0 months (IQR 6-100 months). High radiotherapy dose correlated with better outcomes. After classifying into the SaRT, SbRT, and ScRT groups, three notably different curves were obtained for long-term post-SBRT survival and intrahepatic control. On multivariate analysis, higher radiation dose was associated with improved OS, PFS, and intrahepatic control. Conclusions If tolerated by normal tissue, we recommend SaRT (BED10 >= 100 Gy) as a first-line ablative dose or SbRT (EQD(2) >= 74 Gy) as a second-line radical dose. Otherwise, ScRT (EQD(2) < 74 Gy) is recommended as palliative irradiation.