Distance to isocenter is not associated with an increased risk for local failure in LINAC-based single-isocenter SRS or SRT for multiple brain metastases

•Growing evidence for stereotactic radiotherapy in multiple brain metastases.•Convenient and fast LINAC-treatment of multiple lesions with one isocenter (SIMT).•Concerns of uncertainties on target coverage at extended distances to isocenter.•Distance to isocenter does not impact local control with S...

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Published in:Radiotherapy and oncology 2021-06, Vol.159, p.168-175
Main Authors: Kraft, Johannes, van Timmeren, Janita E., Mayinger, Michael, Frei, Simon, Borsky, Kim, Stark, Luisa Sabrina, Krayenbuehl, Jerome, Zamburlini, Mariangela, Guckenberger, Matthias, Tanadini-Lang, Stephanie, Andratschke, Nicolaus
Format: Article
Language:English
Subjects:
Brain metastases
Radiosurgery
Single isocenter multiple targets technique
Stereotactic radiotherapy
VMAT
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Summary:•Growing evidence for stereotactic radiotherapy in multiple brain metastases.•Convenient and fast LINAC-treatment of multiple lesions with one isocenter (SIMT).•Concerns of uncertainties on target coverage at extended distances to isocenter.•Distance to isocenter does not impact local control with SIMT SRS/SRT. To evaluate the impact of the distance between treatment isocenter and brain metastases on local failure in patients treated with a frameless linear-accelerator-based single-isocenter volumetric modulated arc (VMAT) SRS/SRT for multiple brain metastases. Patients treated with SRT for brain metastases (BM) between April 2014 and May 2019 were included in this retrospective study. BM treated with a single-isocenter multiple-target (SIMT) SRT were evaluated for local recurrence-free intervals in dependency to their distance to the treatment isocenter. A Cox-regression model was used to investigate different predictor variables for local failure. Results were compared to patients treated with a single-isocenter-single-target (SIST) approach. In total 315 patients with a cumulative number of 1087 BM were analyzed in this study of which 140 patients and 708 BM were treated with SIMT SRS/SRT. Median follow-up after treatment was 13.9 months for SIMT approach and 11.9 months for SIST approach. One-year freedom from local recurrence was 87% and 94% in the SIST and SIMT group, respectively. Median distance to isocenter (DTI) was 4.7 cm (range 0.2–10.5) in the SIMT group. Local recurrence-free interval was not associated with the distance to the isocenter in univariable or multivariable Cox-regression analysis. Multivariable analysis revealed only volume as an independent significant predictor for local failure (p-value
ISSN:0167-8140
1879-0887
DOI:10.1016/j.radonc.2021.03.022