title: Age and radiation response in glioblastoma multiforme.
abstract: OBJECTIVE
  Advanced age is a strong predictor of shorter survival in patients with glioblastoma multiforme (GM), especially for those who receive multimodality treatment. Radiographically assessed tumor response to external beam radiation therapy is an important prognostic factor in GM. We hypothesized that older GM patients might have more radioresistant tumors.
  
  
  METHODS
  We studied radiographically assessed response to external beam radiation treatment (five-level scale) in relation to age and other prognostic factors in a cohort of 301 GM patients treated on two prospective clinical protocols. A total of 223 patients (74%) were assessable for radiographically assessed radiation response. A proportional odds ordinal regression model was used for univariate and multivariate analysis.
  
  
  RESULTS
  Younger age (P = 0.006), higher Karnofsky Performance Scale score before radiotherapy (P = 0.027), and more extensive surgical resection (P = 0.028) predicted better radiation response in univariate analyses. Results were similar when clinical criteria were used to classify an additional 61 patients without radiographically assessed radiation response (stable versus progressive disease). In multivariate analyses, age and extent of resection were significant independent predictors of radiation response (P < 0.05); Karnofsky Performance Scale score was of borderline significance (P = 0.07).
  
  
  CONCLUSIONS
  Older GM patients are less likely to have good responses to postoperative external beam radiation therapy. Karnofsky Performance Scale score before radiation treatment and extent of surgical resection are additional predictors of radiographically assessed radiation response in GM.
authors.affiliation: Neuro-Oncology Service, Brain Tumor Research Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, USA. barker@helix.mgh.harvard.edu
authors.forename: F G
authors.initials: FG
authors.lastname: Barker
authors.forename: S M
authors.initials: SM
authors.lastname: Chang
authors.forename: D A
authors.initials: DA
authors.lastname: Larson
authors.forename: P K
authors.initials: PK
authors.lastname: Sneed
authors.forename: W M
authors.initials: WM
authors.lastname: Wara
authors.forename: C B
authors.initials: CB
authors.lastname: Wilson
authors.forename: M D
authors.initials: MD
authors.lastname: Prados
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D015331:Cohort Studies; D003131:Combined Modality Therapy; D016371:Cranial Irradiation; D019583:Dose Fractionation, Radiation; D005909:Glioblastoma / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D016017:Odds Ratio; D011859:Radiography; D018714:Radiotherapy, Adjuvant; D015996:Survival Rate; D016896:Treatment Outcome