Intraoperative radiotherapy (IORT) for surgically resected brain metastases: outcome analysis of an international cooperative study
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Background and objective
The ideal delivery of radiation to the surgical cavity of brain metastases (BMs) remains the subject of debate. Risks of local failure (LF) and radiation necrosis (RN) have prompted a reappraisal of the timing and/or modality of this critical component of BM management. IORT delivered at the time of resection for BMs requiring surgery offers the potential for improved local control (LC) afforded by the elimination of delay in time to initiation of radiation following surgery, decreased uncertainty in target delineation, and the possibility of dose escalation beyond that seen in stereotactic radiosurgery (SRS). This study provides a retrospective analysis with identification of potential predictors of outcomes.
Retrospective data was collected on patients treated with IORT immediately following surgical resection of BMs at three institutions according to the approval of individual IRBs. All patients were treated with 50kV portable linear accelerator using spherical applicators ranging from 1.5 to 4.0 cm. Statistical analyses were performed using IBM SPSS with endpoints of LC, DBC, incidence of RN, and overall survival (OS) and p < 0.05 considered significant.
54 patients were treated with IORT with a median age of 64 years. The most common primary diagnosis was non-small cell lung cancer (40%) with the most common location in the frontal lobe (38%). Median follow-up was 7.2 months and 1-year LC, DBC, and OS were 88%, 58%, and 73%, respectively. LMD was identified in 2 patients (3%) and RN present in 4 patients (7%). The only predictor of LC was extent of resection with 1-year LC of 94% for GTR versus 62% for STR (p = 0.049).
IORT is a safe and effective means of delivering adjuvant radiation to the BM resection cavities with high rates of LC and low incidence of RN. Further studies are warranted directly comparing LC outcomes to SRS.
KeywordsBrain metastases IORT Intraoperative radiotherapy
Each of the authors performed the following tasks in submission of this manuscript: CPC—Study design, Data Collection, Statistical Analysis, Manuscript Drafting, Review/Revision of Manuscript. SB—Data Collection, Review/Revision of Manuscript. JAV—Study design, Data Collection, Statistical Analysis, Manuscript Drafting, Review/Revision of Manuscript. JDH—Data Collection, Review/Revision of Manuscript. KHK—Data Collection, Review/Revision of Manuscript. GSV—Data Collection, Review/Revision of Manuscript. FAG—Data Collection, Review/Revision of Manuscript
Funding support was provided to CPC by the NIH/NIGMS via P20GM121322-01A1. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Compliance with ethical standards
Conflict of interest
Dr. Kahl reports personal fees from ELEKTA AB, personal fees from Varian, outside of the submitted work. Dr. Sarria reports grants and personal fees from Carl Zeiss Meditec AG, outside of the submitted work. Dr. Giordano reports grants and personal fees from Carl Zeiss Meditec AG, during the conduct of the study; grants and personal fees from NOXXON Pharma AG, grants and personal fees from ELEKTA AB, personal fees from Bristol-Myers Squibb, personal fees from Roche Pharma AG, personal fees from MSD Sharp and Dohme GmbH, personal fees from AstraZeneca GmbH, other from Implacit GmbH, non-financial support from Oncare GmbH, outside the submitted work; In addition, Dr. Giordano has a patent Radiation Therapy with Immune Response Monitoring (US 62/435405) pending to Carl Zeiss Meditec AG. All other authors have no disclosures relevant to the submitted work.
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