title: Daily megavoltage computed tomography in lung cancer radiotherapy: correlation between volumetric changes and local outcome.
abstract: OBJECTIVE
  To assess the predictive or comparative value of volumetric changes, measured on daily megavoltage computed tomography during radiotherapy for lung cancer.
  
  
  METHODS
  We included 80 patients with locally advanced non-small-cell lung cancer treated with image-guided intensity-modulated radiotherapy. The radiotherapy was combined with concurrent chemotherapy, combined with induction chemotherapy, or given as primary treatment. Patients entered two parallel studies with moderately hypofractionated radiotherapy. Tumor volume contouring was done on the daily acquired images. A regression coefficient was derived from the volumetric changes on megavoltage computed tomography, and its predictive value was validated. Logarithmic or polynomial fits were applied to the intratreatment changes to compare the different treatment schedules radiobiologically.
  
  
  RESULTS
  Regardless of the treatment type, a high regression coefficient during radiotherapy predicted for a significantly prolonged cause-specific local progression free-survival (p = 0.05). Significant differences were found in the response during radiotherapy. The significant difference in volumetric treatment response between radiotherapy with concurrent chemotherapy and radiotherapy plus induction chemotherapy translated to a superior long-term local progression-free survival for concurrent chemotherapy (p = 0.03). An enhancement ratio of 1.3 was measured for the used platinum/taxane doublet in comparison with radiotherapy alone.
  
  
  CONCLUSIONS
  Contouring on daily megavoltage computed tomography images during radiotherapy enabled us to predict the efficacy of a given treatment. The significant differences in volumetric response between treatment strategies makes it a possible tool for future schedule comparison.
authors.affiliation: Department of Radiation Oncology, Oncology Center, Universitair Ziekenhuis Brussel, Brussels, Belgium. samuelbral@yahoo.co.uk
authors.forename: Samuel
authors.initials: S
authors.lastname: Bral
authors.forename: Mark
authors.initials: M
authors.lastname: De Ridder
authors.forename: Michaël
authors.initials: M
authors.lastname: Duchateau
authors.forename: Thierry
authors.initials: T
authors.lastname: Gevaert
authors.forename: Benedikt
authors.initials: B
authors.lastname: Engels
authors.forename: Denis
authors.initials: D
authors.lastname: Schallier
authors.forename: Guy
authors.initials: G
authors.lastname: Storme
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D003131:Combined Modality Therapy / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012074:Remission Induction / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden / Q000528:radiation effects*