Local control and toxicity outcomes in brainstem metastases treated with single fraction radiosurgery: is there a volume threshold for toxicity?

J Neurooncol. 2014 Mar;117(1):167-74. doi: 10.1007/s11060-014-1373-x. Epub 2014 Feb 7.

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.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Stem / pathology
  • Brain Stem Neoplasms / pathology
  • Brain Stem Neoplasms / secondary*
  • Brain Stem Neoplasms / surgery*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cause of Death
  • Dose Fractionation, Radiation
  • Dose-Response Relationship, Radiation
  • Female
  • Follow-Up Studies
  • Humans
  • Kaplan-Meier Estimate
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Radiosurgery / adverse effects*
  • Retrospective Studies
  • Time Factors
  • Treatment Outcome
  • Tumor Burden