Dynamic tumor-tracking stereotactic body radiotherapy with real-time monitoring of liver tumors using a gimbal-mounted linac: A multi-institutional phase II study

Yusuke Iizuka; Masahiro Hiraoka; Masaki Kokubo; Takashi Sakamoto; Katsuyuki Karasawa; Keiko Murofushi; Mitsuhiro Nakamura; Yukinori Matsuo; Satoshi Morita; Haruo Inokuchi; Takashi Mizowaki

doi:10.1016/j.ctro.2023.100591

Dynamic tumor-tracking stereotactic body radiotherapy with real-time monitoring of liver tumors using a gimbal-mounted linac: A multi-institutional phase II study

Clin Transl Radiat Oncol. 2023 Feb 10:39:100591. doi: 10.1016/j.ctro.2023.100591. eCollection 2023 Mar.

Authors

Affiliations

¹ Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, Japan.
² Department of Radiation Oncology, Japanese Red Cross Society Wakayama Medical Center, Japan.
³ Department of Radiation Oncology, Kobe City Medical Center General Hospital, Japan.
⁴ Department of Radiation Oncology, Kyoto Katsura Hospital, Japan.
⁵ Division of Radiation Oncology, Department of Radiology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Japan.
⁶ Division of Medical Physics, Department of Information Technology and Medical Engineering, Human Health Sciences, Kyoto University, Japan.
⁷ Department of Biomedical Statistics and Bioinformatics, Kyoto University Graduate School of Medicine, Japan.

Abstract

Background and purpose: This prospective multicenter phase II study aimed to evaluate the safety and efficacy of dynamic tumor tracking (DTT) stereotactic body radiotherapy (SBRT) with real-time monitoring of liver tumors using a gimbal-mounted system.

Materials and methods: Patients with < 4 primary or metastatic liver tumors with diameters ≤ 50 mm and expected to have a respiratory motion of ≥ 10 mm were eligible. The prescribed dose was 40 Gy in five fractions. The primary endpoint was local control (LC) at 2 years. The secondary endpoints were overall survival (OS), progression-free survival (PFS), treatment-related toxicity, and tracking accuracy.

Results: Between September 2015 and March 2019, 48 patients (48 lesions) with a median age of 74 years were enrolled from four institutions. Of these, 39 were diagnosed with hepatocellular carcinoma and nine with metastatic liver cancer. The median tumor diameter was 17.5 mm. DTT-SBRT was successfully performed in all patients; the median treatment time was 28 min/fraction. The median follow-up period was 36.5 months. The 2-year LC, OS, and PFS rates were 98.0 %, 88.8 %, and 55.1 %, respectively. Disease progression was observed in 33 (68.8 %) patients. One patient (0.2 %) had local recurrence, 31 (64.6 %) developed new hepatic lesions outside the irradiation field, and nine (18.8 %) had distant metastases (including overlap). Grade 3 late adverse events were observed in seven patients (14.5 %). No grade 4 or 5 treatment-related toxicity was observed. The median tracking accuracy was 2.9 mm.

Conclusion: Employing DTT-SBRT to treat liver tumors results in excellent LC with acceptable adverse-event incidence.

Keywords: 4D, four-dimensional; CT, computed tomography; CTV, clinical target volume; DTT, dynamic tumor tracking; Dynamic tumor tracking; GTV, gross tumor volume; HCC, hepatocellular carcinoma; IR, infrared; LC, local control; Liver; Malignant neoplasms; Metastasis; OAR, organs at risk; OS, overall survival; PFS, progression-free survival; PTV, planning target volume; RFA, radiofrequency ablation; SBRT, stereotactic body radiotherapy; Stereotactic body radiotherapy; TV, target volume.