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Purpose: Surgically targeted radiation therapy (STaRT) with Cesium-131 seeds embedded in a collagen tile is a promising treatment for recurrent brain metastasis. In this study, the biological effective doses (BED) for normal and target tissues from STaRT plans were compared with those of external beam radiotherapy (EBRT) modalities., Methods: Nine patients (n = 9) with 12 resection cavities (RCs) who underwent STaRT (cumulative physical dose of 60 Gy to a depth of 5 mm from the RC edge) were replanned with CyberKnife Ⓡ (CK), Gamma Knife Ⓡ (GK), and intensity modulated proton therapy (IMPT) using an SRT approach (30 Gy in 5 fractions). Statistical significance comparing D95% and D90% in BED 10Gy (BED 10Gy 95% and BED 10Gy 90%) and to RC + 0 to + 5 mm expansion margins, and parameters associated with radiation necrosis risk (V8 3Gy , V10 3Gy , V12 3Gy and V24 3Gy ) to the normal brain were evaluated by a Wilcoxon-signed rank test., Results: For RC + 0 mm, median BED 10Gy 90% for STaRT (90.1 Gy 10 , range: 64.1-140.9 Gy 10 ) was significantly higher than CK (74.3 Gy 10 , range:59.3-80.4 Gy 10 , p = 0.04), GK (69.4 Gy 10 , range: 59.8-77.1 Gy 10 , p = 0.005), and IMPT (49.3 Gy 10 , range: 49.0-49.7 Gy 10 , p = 0.003), respectively. However, for the RC + 5 mm, the median BED 10Gy 90% for STaRT (34.1 Gy 10 , range: 22.2-59.7 Gy 10 ) was significantly lower than CK (44.3 Gy 10 , range: 37.8-52.4 Gy 10 ), and IMPT (46.6 Gy 10 , range: 45.1-48.5 Gy 10 ), respectively, but not significantly different from GK (34.1 Gy 10 , range: 22.8-47.0 Gy 10 ). The median V24 3Gy was significantly higher in CK (11.7 cc, range: 4.7-20.1 cc), GK(6.2 cc, range: 2.3-11.9 cc) and IMPT (19.9 cc, range: 11.1-36.6 cc) compared to STaRT (1.1 cc, range: 0.0-7.8 cc) (p < 0.01)., Conclusions: This comparative analysis suggests a STaRT approach may treat recurrent brain tumors effectively via delivery of higher radiation doses with equivalent or greater BED up to at least 3 mm from the RC edge as compared to EBRT approaches., Competing Interests: Disclosure Tugce Kutuk: None. Rupesh Kotecha: Honoraria from Accuray Inc., Elekta AB, ViewRay Inc., Novocure Inc., Elsevier Inc., Brainlab, Kazia Therapeutics, Castle Biosciences, and institutional research funding from Medtronic Inc., Blue Earth Diagnostics Ltd., Novocure, Inc., GT Medical Technologies, AstraZeneca, Exelixis, ViewRay, Inc., Brainlab, Cantex Pharmaceuticals, and Kazia Therapeutics. Roberto Herrera: None. DJay J Wieczorek: None. Zachary W. Fellows: None. Vibha Chaswal: None. Alonso La Rosa: None. Vivek Mishra: None. Michael W McDermott: Consultant Deinde Medical and Stryker Medical. Vitaly Siomin: None. Minesh P Mehta: Consulting fees from Karyopharm, Sapience, Zap, Mevion, Xoft, BOD Oncoceutics, Kazia Therapeutics; stock in Chimerix. Alonso N Gutierrez: Honoraria from ViewRay, Inc., Elekta AB, IBA AB. Ranjini Tolakanahalli: None., (Copyright © 2024 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: This study evaluates the outcomes of recurrent brain metastasis treated with resection and brachytherapy using a novel Cesium-131 carrier, termed surgically targeted radiation therapy (STaRT), and compares them to the first course of external beam radiotherapy (EBRT)., Methods: Consecutive patients who underwent STaRT between August 2020 and June 2022 were included. All patients underwent maximal safe resection with pathologic confirmation of viable disease prior to STaRT to 60 Gy to a 5-mm depth from the surface of the resection cavity. Complications were assessed using CTCAE version 5.0., Results: Ten patients with 12 recurrent brain metastases after EBRT (median 15.5 months, range: 4.9-44.7) met the inclusion criteria. The median BED 10Gy 90% and 95% were 132.2 Gy (113.9-265.1 Gy) and 116.0 Gy (96.8-250.6 Gy), respectively. The median maximum point dose BED 10Gy for the target was 1076.0 Gy (range: 120.7-1478.3 Gy). The 6-month and 1-year local control rates were 66.7% and 33.3% for the prior EBRT course; these rates were 100% and 100% for STaRT, respectively (p < 0.001). At a median follow-up of 14.5 months, there was one instance of grade two radiation necrosis. Surgery-attributed complications were observed in two patients including pseudomeningocele and minor headache., Conclusions: STaRT with Cs-131 presents an alternative approach for operable recurrent brain metastases and was associated with superior local control than the first course of EBRT in this series. Our initial clinical experience shows that STaRT is associated with a high local control rate, modest surgical complication rate, and low radiation necrosis risk in the reirradiation setting., (Copyright © 2023 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)