Hering S, Nieto A, Marschner S, Hofmaier J, Schmidt-Hegemann NS, da Silva Mendes V, Landry G, Niyazi M, Manapov F, Belka C, Corradini S, and Eze C
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 cm 3 (range: 3.4 - 96.5 cm 3 ). 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% (BED 10 ) 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% (BED 10 ) 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., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The Department of Radiation Oncology of the LMU University Hospital, LMU Munich has research agreements with ViewRay Inc., Elekta, Brainlab, and C-RAD. ViewRay Inc. did not fund this study and was not involved and had no influence on the study design, the collection or analysis of data, or on the writing of the manuscript. MN reports research grants and speaker fees/travel support from Brainlab, ViewRay, AstraZeneca. FM reports a research grant from AstraZeneca and honoraria from AstraZeneca, Novartis, Roche, Lilly, Elekta and Brainlab. FM serves on the advisory board of AstraZeneca, Novartis. CB reports receiving grants or contracts from ViewRay, Brainlab, and Elekta; payment or honoraria from Bristol-Myers Squibb, Roche, Merck, AstraZeneca, Opasca, C-RAD, Elekta, and ViewRay; receiving support for attending meetings or travel from Bristol-Myers Squibb, Roche, Merck, AstraZeneca, Elekta, and View Ray; and having a leadership or fiduciary role with ESTRO, all outside the submitted work. SC reports research grants and speaker fees/travel support from Elekta, Viewray and Brainlab. CE reports consulting fees from Novartis outside the submitted work., (© 2024 The Author(s).)