Radiosurgery for Five to Fifteen Brain Metastases: A Single Centre Experience and a Review of the Literature

Abstract

PurposeStereotactic radiosurgery (SRS) is now mainstream for patients with 1-4 brain metastases however the management of patients with 5 or more brain metastases remains controversial. Our aim was to evaluate the clinical outcomes of patients with 5 or more brain metastases and to compare with published series as a benchmarking exercise.MethodsPatients with 5 or more brain metastases treated with a single isocentre dynamic conformal arc technique on a radiosurgery linac were identified from the institutional database. Endpoints were local control, distant brain failure, leptomeningeal disease and overall survival. Dosimetric data were extracted from the radiosurgery plans. Series reporting outcomes following SRS for multiple brain metastases were identified by a literature search.Results36 patients, of whom 35 could be evaluated, received SRS for 5 or more brain metastases between February 2015 and October 2021. 25 patients had 5-9 brain metastases (group 1) and 10 patients had 10-15 brain metastases (group 2). The mean number of brain metastases in group 1 was 6.3 (5-9) and 12.3 (10-15) in group 2. The median cumulative irradiated volume was 4.6 cm3 (1.25-11.01) in group 1 and 7.2 cm3 (2.6-11.1) in group 2. Median follow-up was 12 months. At last follow-up, local control rates per BM were 100% and 99.8% as compared with a median of 87% at 1 year in published series. Distant brain failure was 36% and 50% at a median interval of 5.2 months and 7.4 months after SRS in groups 1 and 2 respectively and brain metastasis velocity at 1 year was similar in both groups (9.7 and 11). 8/25 patients received further SRS and 7/35 patients received whole brain radiotherapy. Median overall survival was 10 months in group 1 and 15.7 months in group 2, which compares well with the 7.5 months derived from the literature. There was one neurological death in group 2, leptomeningeal disease was rare (2/35) and there were no cases of radionecrosis.ConclusionWith careful patient selection, overall survival following SRS for multiple brain metastases is determined by the course of the extracranial disease. SRS is an efficacious and safe modality that can achieve intracranial disease control and should be offered to patients with 5 or more brain metastases and a constellation of good prognostic factors.

Single isocenter dynamic conformal arcs-based radiosurgery for brain metastases: Dosimetric comparison with Cyberknife and clinical investigation

“…In the report of CK including 233 brain metastases in 97 patients, toxicities ≥ grade 3 was not observed [20] . Also, in the report from MBM for 5–15 brain metastases, there was no toxicities ≥ grade 3 [18] . Our results suggested that MBM has steeper dose distribution, but both are considered to be equivalent in clinical practice.…”

“…These techniques achieve favorable dose distribution [13] , [14] , [15] , [16] , [17] . Also, Rogers et al reported favorable results of MBM that local control was 100 % and 99.8 % for patients with 5–9 brain metastases and 10–15 brain metastases [18] .…”

The Impact of Multileaf Collimator Size on Single Isocenter Dynamic Conformal Arcs-Based Radiosurgery for Brain Metastases

“…Stereotactic radiosurgery (SRS) is increasingly used for brain metastases [1][2][3] due to improved technology and emergence of single-isocenter SRS solutions in recent years. The dosimetric results of linac-based SRS are comparable to those with cyberknife (CK) and gamma-knife [4][5][6] and multiple brain metastases (MBM) as small as a few millimeters can be targeted.…”