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Abstract
Background: Although helical tomotherapy (HT) tends to increase intermediate-dose spillage by increasing of low-dose region, this has not been fully determined in the clinical setting. Therefore, we investigated treatment outcomes of HT for hepatocellular carcinoma (HCC) with respect to intermediate-dose spillage.

Methods: We retrospectively reviewed 20 HCC patients, who received high-dose radiotherapy (RT) using HT with radical intent between April 2014 and September 2017. In accordance with the Barcelona Clinic Liver Cancer (BCLC) classification, stage was 0 in 7 patients, A in 3 patients, B in 5 patients, and C in 5 patients. Baseline Child-Pugh class was A in 18 patients and B in 2 patients. The median tumor size was 2.5 cm (range, 1-11 cm). Helical intensity-modulated radiotherapy (IMRT) technique was applied in all patients: among these, 13 patients were treated with stereotactic body radiotherapy (SBRT). The median fraction size was 12 Gy (range, 2-15 Gy), and the median total dose was 50 Gy (range, 44-60 Gy). Intermediate-dose spillage was assessed by the Radiation Therapy Oncology Group recommendation from 22 HT planning data, as follows: R50% means the ratio of the 50% prescription isodose volume to the planning target volume (PTV).

Results: The median follow-up period after HT was 22 months. The local progression-free survival (LPFS) and progression-free survival (PFS) rates were 89% and 59% at 1 year, and 82% and 30% at 2 years, respectively. The overall survival rate was 100% at 1 year and 85% at 2 years, respectively. In terms of intermediate-dose spillage, minor or major deviations were noted in the R50% of 20 HT plans (91%). However, 1 patient (5%) experienced classic radiation-induced liver disease, and severe toxicity ≥ grade 3 was not reported.

Conclusions: Although HT for HCC tends to increase intermediate-dose spillage, the treatment results were favorable with that reported in other published studies.

Affiliations

Sun Hyun Bae  1 , Kwang Hwan Cho  1 , Young Seok Kim  2 , Sang Gyune Kim  2 , Jeong-Ju Yoo  2 , Jae Myung Lee  3 , Min Hee Lee  3 , Sanghyeok Lim  3 , Jae Hong Jung  4 , Sung Hee Lim  5
1 Department of Radiation Oncology, Soonchunhyang University College of Medicine, Bucheon, Korea.
2 Division of Gastroenterology and Hepatology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Bucheon, Korea.
3 Department of Radiology, Soonchunhyang University College of Medicine, Bucheon, Korea.
4 Department of General Surgery, Soonchunhyang University College of Medicine, Bucheon, Korea.
5 Division of Hematology-Oncology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Bucheon, Korea.