Treatment Outcomes Of Stereotactic Body Radiation Therapy Using A Real-Time Tumor-Tracking Radiotherapy System For Hepatocellular Carcinomas

Aim To report the outcomes of stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system for hepatocellular carcinoma patients.Methods From January 2005 to July 2018, 63 patients with 74 lesions with a maximum diameter <= 52 mm were treated by stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system. No patient with a Child-Pugh Score >= 9 was included, and 85.6% had a score of 5 or 6. Using the biological effective dose (BED) with an alpha/beta ratio of 10 (BED10), the median dose in BED10 at the reference point was 76.8 Gy (range 60-122.5 Gy). Overall survival (OS) and local control rates were assessed using the Kaplan-Meier method.Results With a median follow-up period of 24.6 months (range 0.9-118.4 months), the 1-year and 2-year OS rates were 86.8% (95% confidence interval [95% CI] 75.8-93.3) and 71.1% (57.8-81.6), respectively. The 2-year OS was 89.6% in patients with the baseline modified albumin-bilirubin (mALBI) grade =1, and 61.7% in patients with grade >= 2a. In the multivariate analysis, the mALBI grade (=1 vs. >= 2a) was a significant factor for OS (p = 0.028, 95% CI 1.11-6.18). The 1-year and 2-year local control rates were 100% (100-100%) and 92.0% (77.5-97.5%). The local control rates were significantly higher in the BED10 >= 100 Gy group than in the BED10 <100 Gy group (2-year 100% vs. 86.5%, p = 0.049) at the reference point.Conclusion This retrospective study of stereotactic body radiotherapy using real-time tumor-tracking radiotherapy for hepatocellular carcinoma showed favorable outcomes with lower incidence of toxicities, especially in patients treated with BED10 >= 100 Gy to the reference point.