Long-Term Outcome of a Multicenter Prospective Study on Efficacy and Safety of High-Dose Stereotactic Body Radiation Therapy ≥48-h Interfraction Interval for ≤5 cm Hepatocellular Carcinoma

Introduction: The goal of this study was to evaluate the efficacy and safety of high-dose stereotactic body radiation therapy (SBRT) with an extended (48 h or more) interfraction interval for hepatocellular carcinoma (HCC) ≥5 cm in size after incomplete response to transarterial chemoembolization (TACE). Methods: This multicenter prospective study included 54 patients with inoperable HCC of ≥5 cm size between July 2012 and June 2015. A total SBRT dose of 60 Gy in 3 fractions was administered within 14 days with ≥48-h interfraction interval to patients who showed an incomplete response after 1-5 sessions of TACE. Treatment responses were defined according to the modified Response Evaluation Criteria for Solid Tumors. Toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. Results: Forty-eight patients were evaluated with a median follow-up period of 66 months (range, 2-126 months). The median tumor size was 2.0 cm (range, 1.0-4.5 cm), and most patients (87.5%) had a single lesion. The 1-, 2-, and 5-year local control (LC) rates were 100%, 94.8%, and 90.7%, respectively. The 1-, 2-, and 5-year progression-free survival (PFS) rates were 63.4%, 56.9%, and 24.9%, respectively. The 1-, 2-, and 5-year overall survival (OS) rates were 95.6%, 90.9%, and 76.5%, respectively. None of the patients experienced grade 3+ gastrointestinal toxicity, while 1 patient developed non-classic radiation-induced liver disease 2 months after SBRT. Conclusion: High-dose SBRT with a ≥48-h interfraction interval after incomplete response to TACE is effective for HCC ≥5 cm in size as evidenced by the high rates of LC and OS and acceptable treatment-related toxicity.