title: Radiation-induced brain injury: retrospective analysis of twelve pathologically proven cases.
abstract: OBJECTIVE
  This study was designed to determine the influencing factors and clinical course of pathologically proven cases of radiation-induced brain injury (RIBI).
  
  
  METHODS
  The pathologic records of twelve patients were reviewed; these patients underwent surgery following radiotherapy due to disease progression found by follow-up imaging. However, they were finally diagnosed with RIBI. All patients had been treated with 3-dimensional conventional fractionated radiotherapy and/or radiosurgery for primary or metastatic brain tumors with or without chemotherapy. The histological distribution was as follows: two falx meningioma, six glioblastoma multiform (GBM), two anaplastic oligodendroglioma, one low grade oligodendroglioma, and one small cell lung cancer with brain metastasis.
  
  
  RESULTS
  Radiation necrosis was noted in eight patients and the remaining four were diagnosed with radiation change. Gender (p = 0.061) and biologically equivalent dose (BED)(3) (p = 0.084) were the only marginally influencing factors of radiation necrosis. Median time to RIBI was 7.3 months (range, 0.5 to 61 months). Three prolonged survivors with GBM were observed. In the subgroup analysis of high grade gliomas, RIBI that developed <6 months after radiotherapy was associated with inferior overall survival rates compared to cases of RIBI that occurred ≥6 months (p = 0.085).
  
  
  CONCLUSIONS
  Our study demonstrated that RIBI could occur in early periods after conventional fractionated brain radiotherapy within normal tolerable dose ranges. Studies with a larger number of patients are required to identify the strong influencing factors for RIBI development.
authors.affiliation: Department of Radiation Oncology, The Cancer Center of Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Dong-Soo
authors.initials: DS
authors.lastname: Lee
authors.forename: Mina
authors.initials: M
authors.lastname: Yu
authors.forename: Hong-Seok
authors.initials: HS
authors.lastname: Jang
authors.forename: Yeon-Sil
authors.initials: YS
authors.lastname: Kim
authors.forename: Byung-Ock
authors.initials: BO
authors.lastname: Choi
authors.forename: Young-Nam
authors.initials: YN
authors.lastname: Kang
authors.forename: Youn-Soo
authors.initials: YS
authors.lastname: Lee
authors.forename: Dong-Chul
authors.initials: DC
authors.lastname: Kim
authors.forename: Yong-Kil
authors.initials: YK
authors.lastname: Hong
authors.forename: Sin-Soo
authors.initials: SS
authors.lastname: Jeun
authors.forename: Sei-Chul
authors.initials: SC
authors.lastname: Yoon