Effect of CyberKnife stereotactic body radiation therapy for hepatocellular carcinoma on hepatic toxicity

OBJECTIVE To evaluate the safety of CyberKnife stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) patients and identify the treatment-related risk factors of hepatic toxicity. MATERIALS AND METHODS One hundred and four HCC patients treated with CyberKnife SBRT were included in this study between August 2009 and December 2012. The average dose of prescribed radiation was 42.81±4.78 Gy (28-55 Gy) with the average fraction size of 8-16 Gy to the planning target volume. The average fractions were 3.31±0.81 (2-6 fractions). Response rates were determined, and the Child-Pugh (CP) score and class following CyberKnife SBRT were obtained to evaluate hepatic toxicity. RESULTS Seventeen patients experienced progression in CP class and 24 patients experienced CTCAE V. 4.0 grade 2-3 hepatic toxicity during the five-month follow-up period, while no patient experienced grade 4 liver toxicity. Multivariate analysis indicated that only V25 was an independent factor in grade 2-3 hepatic toxicity (P=0.029, <0.05). Radiation-induced hepatic toxicity (RIHT), defined as an increase of at least two points within three months following CyberKnife SBRT, occurred in 13 of the 104 patients (13/104, 12.5%), and only the normal liver tissue was found to be associated with RIHT (P=0.008, <0.05). CONCLUSION CyberKnife SBRT is a feasible and safe treatment for HCC with regard to hepatic toxicity, while V25 and normal liver volume may be an independent factor of grade 2-3 hepatic toxicity and RIHT, respectively.