The role of online MR-guided multi-fraction stereotactic ablative radiotherapy in lung tumours

Svenja Hering; Alexander Nieto; Sebastian Marschner; Jan Hofmaier; Nina-Sophie Schmidt-Hegemann; Vanessa da Silva Mendes; Guillaume Landry; Maximilian Niyazi; Farkhad Manapov; Claus Belka; Stefanie Corradini; Chukwuka Eze

doi:10.1016/j.ctro.2024.100736

The role of online MR-guided multi-fraction stereotactic ablative radiotherapy in lung tumours

Clin Transl Radiat Oncol. 2024 Jan 30:45:100736. doi: 10.1016/j.ctro.2024.100736. eCollection 2024 Mar.

Authors

Affiliations

¹ Department of Radiation Oncology, LMU University Hospital, LMU Munich, Munich, Germany.
² Department of Radiation Oncology, University of Tübingen, Tübingen, Germany.
³ Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Munich, Germany.
⁴ German Cancer Consortium (DKTK), partner site Munich; and German Cancer Research Center (DKFZ), Heidelberg, Germany.
⁵ Bavarian Cancer Research Center (BZKF), Munich, Germany.

Abstract

Background: The aim of this prospective observational study was to evaluate the dosimetry benefits, changes in pulmonary function, and clinical outcome of online adaptive MR-guided SBRT.

Methods: From 11/2020-07/2022, 45 consecutive patients with 59 lesions underwent multi-fraction SBRT (3-8 fractions) at our institution. Patients were eligible if they had biopsy-proven NSCLC or lung cancer/metastases diagnosed via clinical imaging. Endpoints were local control (LC) and overall survival (OS). We evaluated PTV/GTV dose coverage, organs at risk exposure, and changes in pulmonary function (PF). Acute toxicity was classified per the National Cancer Institute-Common Terminology Criteria for Adverse Events version 5.0.

Results: The median PTV was 14.4 cm³ (range: 3.4 - 96.5 cm³). In total 195/215 (91%) plans were reoptimised. In the reoptimised vs. predicted plans, PTV coverage by the prescribed dose increased in 94.6% of all fractions with a median increase in PTV V_PD of 5.6% (range: -1.8 - 44.6%, p < 0.001), increasing the number of fractions with PTV V_PD ≥ 95% from 33% to 98%. The PTV D_95% and D_98% (BED₁₀) increased in 93% and 95% of all fractions with a median increase of 7.7% (p < 0.001) and 10.6% (p < 0.001). The PTV D_95% (BED₁₀) increased by a mean of 9.6 Gy (SD: 10.3 Gy, p < 0.001). At a median follow-up of 21.4 months (95% CI: 12.3-27.0 months), 1- and 2-year LC rates were 94.8% (95% CI: 87.6 - 100.0%) and 91.1% (95% CI: 81.3 - 100%); 1- and 2-year OS rates were 85.6% (95% CI: 75.0 - 96.3%) and 67.1 % (95% CI: 50.3 - 83.8%). One grade ≥ 3 toxicity and no significant reduction in short-term PF parameters were recorded.

Conclusions: Online adaptive MR-guided SBRT is an effective, safe and generally well tolerated treatment option for lung tumours achieving encouraging local control rates with significantly improved target volume coverage.

Keywords: Lung cancer; MR-Linac, SBRT, SABR, lung metastases; MR-guided SABR; MR-guided SBRT; MR-guided radiotherapy; Radiation oncology.