title: Can MRI-derived factors predict the survival in glioblastoma patients treated with postoperative chemoradiation therapy?
abstract: BACKGROUND
  Advanced diagnostic and therapeutic developments may yield novel prognostic factors in patients with glioblastoma multiforme (GBM).
  
  
  OBJECTIVE
  To validate the predictive values of pretreatment quantitative diffusion-weighted (DW) magnetic resonance imaging (MRI) and MRI performed within 72 h after surgery in patients with GBM.
  
  
  METHODS
  Between January 2000 and September 2009, 138 patients with GBM underwent postoperative chemoradiation therapy (chemo-RT) and longitudinal MRI before surgery, in the early postoperative period, and at 1-month intervals thereafter. The role of the patient age, Karnofsky performance scale (KPS) score, minimum apparent diffusion coefficient (ADC) on pretreatment DW-MRI, and gross residual tumor on early postoperative MRI were assessed by factor analysis of overall survival (OS). Survival curves were calculated using the Kaplan-Meier method; the multivariate Cox's proportional hazards model was used to adjust for the influence of prognostic factors. Radiation Therapy Oncology Group-recursive partitioning analysis (RTOG-RPA) criteria were used to validate the predictive value of the MRI-derived factors.
  
  
  RESULTS
  Substantial independent prognostic factors were the KPS score (hazard ratio [HR], 1.812), minimum ADC (HR, 2.365), and gross residual tumor (HR, 1.777). Based on MRI-derived factors, we assigned the patients to different prognostic groups in the RTOG-RPA classification and grouped them according to the level of risk, i.e. a high-risk group with low minimum ADCs (<0.93 × 10(-3) mm(2)/s) with gross residual tumor and a low-risk group with high minimum ADCs (≥0.93 × 10(-3) mm(2)/s) without gross residual tumor; the other patients were assigned to the intermediate-risk group. Median OS for the low-, intermediate-, and high-risk groups were 28.2, 14.7, and 10.8 months, respectively (P < 0.001).
  
  
  CONCLUSIONS
  The minimum ADC on pretreatment DW-MRI and gross residual tumor on early postoperative MRI can predict the survival in GBM patients treated with postoperative chemo-RT.
authors.affiliation: Department of Neurosurgery, Kumamoto University, Kumamoto, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Nakamura
authors.forename: Ryuji
authors.initials: R
authors.lastname: Murakami
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Mika
authors.initials: M
authors.lastname: Kitajima
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000401:mortality* / Q000601:surgery / Q000628:therapy; D059248:Chemoradiotherapy; D002648:Child; D003131:Combined Modality Therapy; D038524:Diffusion Magnetic Resonance Imaging; D018572:Disease-Free Survival; D005260:Female; D005909:Glioblastoma / Q000401:mortality* / Q000601:surgery / Q000628:therapy; D006801:Humans; D017567:Karnofsky Performance Status; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015996:Survival Rate; D055815:Young Adult