title: Local control and toxicity outcomes in brainstem metastases treated with single fraction radiosurgery: is there a volume threshold for toxicity?
abstract: Gamma Knife Radiosurgery (GKRS) has been reported in the treatment of brainstem metastases while dose volume toxicity thresholds remain mostly undefined. A retrospective review of 52 brainstem metastases in 44 patients treated with GKRS was completed. A median dose of 18 Gy (range 10-22 Gy) was prescribed to the tumor margin (median 50 % isodose). 25 patients had undergone previous whole brain radiation therapy. Toxicity was graded by the LENT-SOMA scale. Mean and median follow-up was 10 and 6 months. Only 3 of the 44 patients are living. Multiple brain metastases were treated in 75 % of patients. Median size of lesions was 0.134 cc, (range 0.013-6.600 cc). Overall survival rate at 1 year was 32 % (95 % CI 51.0-20.1 %) with a median survival time of 6 months (95 % CI 5.0-16.5). Local control rate at 6 months and 1 year was 88 % (95 % CI 70-95 %) and 74 % (95 % CI 52-87 %). Cause of death was neurologic in 17 patients, non-neurologic in 20 patients, and unknown in four. Four patients experienced treatment related toxicities. Univariate analysis of tumor volume revealed that volume greater than 1.0 cc predicted for toxicity. A strategy of using lower marginal doses with GKRS to brain stem metastases appears to lead to a lower local control rate than seen with lesions treated within the standard dose range in other locations. Tumor size greater than 1.0 cc predicted for treatment-related toxicity.
authors: Department of Radiation Oncology, Wake Forest School of Medicine, 1 Medical Center Blvd, Winston-Salem, NC, 27157, USA, jkilburn@wakehealth.edu.
authors: Jeremy M
authors: JM
authors: Kilburn
authors: Thomas L
authors: TL
authors: Ellis
authors: James F
authors: JF
authors: Lovato
authors: James J
authors: JJ
authors: Urbanic
authors: J Daniel
authors: JD
authors: Bourland
authors: J
authors: J
authors: Daniel Bourland
authors: Michael T
authors: MT
authors: Munley
authors: Allan F
authors: AF
authors: Deguzman
authors: Kevin P
authors: KP
authors: McMullen
authors: Edward G
authors: EG
authors: Shaw
authors: Stephen B
authors: SB
authors: Tatter
authors: Michael D
authors: MD
authors: Chan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001933:Brain Stem / Q000473:pathology; D020295:Brain Stem Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology; D002423:Cause of Death; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden