title: The Effect of Timing of Concurrent Chemoradiation in Patients With Newly Diagnosed Glioblastoma.
abstract: BACKGROUND
  The effect of timing of initiation of concurrent radiation and chemotherapy after surgery on outcome of patients with glioblastoma (GBM) remains unclear.
  
  
  OBJECTIVE
  To further explore this issue, we analyzed 4 clinical trials for patients newly diagnosed with GBM receiving concurrent and adjuvant temozolomide.
  
  
  METHODS
  The cohort study included 198 adult patients with newly diagnosed supratentorial GBM who were enrolled from 2004 to 2010 in 4 clinical trials consisting of radiation plus temozolomide and an experimental agent. The interval to initiation of therapy was determined from the time of surgical resection. The partitioning deletion/substitution/addition algorithm was used to determine the cutoff points for timing of chemoradiation at which there was a significant difference in overall survival (OS) and progression-free survival (PFS).
  
  
  RESULTS
  The median wait time between surgery and initiation of concurrent chemoradiation was 29.5 days (range, 7-56 days). A short delay in chemoradiation administration (at 30-34 days) was predictive of prolonged OS (hazard ratio [HR]: 0.63, P = .03) and prolonged PFS (HR: 0.68, P = .06) compared with early initiation of concurrent chemoradiation (<30 days), after adjusting for protocol and baseline prognostic variables including extent of resection by multivariate analysis. A longer delay to chemoradiation beyond 34 days was not associated with improved OS or PFS compared with early initiation (HR: 0.94, P = .77 and HR: 0.91, P = .63, respectively).
  
  
  CONCLUSIONS
  A short delay in the start of concurrent chemoradiation is beyond the classic paradigm of 4 weeks post-resection and may be associated with prolonged OS and PFS.
authors: Departments of *Neurological Surgery, ‡Epidemiology and Biostatistics, and §Neurology, University of California at San Francisco, San Francisco, California.
authors: Seunggu J
authors: SJ
authors: Han
authors: W Caleb
authors: WC
authors: Rutledge
authors: Annette M
authors: AM
authors: Molinaro
authors: Susan M
authors: SM
authors: Chang
authors: Jennifer L
authors: JL
authors: Clarke
authors: Michael D
authors: MD
authors: Prados
authors: Jennie W
authors: JW
authors: Taylor
authors: Mitchel S
authors: MS
authors: Berger
authors: Nicholas A
authors: NA
authors: Butowski
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000601:surgery / Q000628:therapy*; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D015331:Cohort Studies; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000627:therapeutic use; D018572:Disease-Free Survival; D005260:Female; D005909:Glioblastoma / Q000601:surgery / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D011379:Prognosis; D016019:Survival Analysis; D000077204:Temozolomide; D016896:Treatment Outcome
chemical_list: D018906:Antineoplastic Agents, Alkylating; D003606:Dacarbazine; D000077204:Temozolomide