title: Clinical implications of the tumor volume reduction rate in head-and-neck cancer during definitive intensity-modulated radiotherapy for organ preservation.
abstract: OBJECTIVE
  To investigate the prognostic value of the volume reduction rate (VRR) in patients with head-and-neck cancer treated with intensity-modulated radiotherapy (IMRT).
  
  
  METHODS
  Seventy-six patients with oropharyngeal cancer (OPC) and another 76 with hypopharyngeal cancer (HPC) were enrolled in volumetric analysis. All patients received allocated radiotherapy courses. Adaptive computed tomography was done 4 to 5 weeks after the start of IMRT. Primary tumor volume measurement was derived using separate images for the pretreatment gross tumor volume (pGTV) and the interval gross tumor volume.
  
  
  RESULTS
  In the OPC group, the pGTV ranged from 6.6 to 242.6 mL (mean, 49.9 mL), whereas the value of the VRR ranged from 0.014 to 0.74 (mean, 0.43). In HPC patients, the pGTV ranged from 4.1 to 152.4 mL (mean, 35.6 mL), whereas the VRR ranged from -1.15 to 0.79 (mean, 0.33). Multivariate analysis of the primary tumor relapse-free survival for OPC revealed three prognostic factors: T4 tumor (p = 0.0001, hazard ratio 7.38), pGTV ≥20 mL (p = 0.01, hazard ratio 10.61), and VRR <0.5 (p = 0.001, hazard ratio 6.49). Multivariate analysis of the primary tumor relapse-free survival for HPC showed two prognostic factors: pGTV ≥30 mL (p = 0.001, hazard ratio 2.87) and VRR <0.5 (p = 0.03, hazard ratio 2.25).
  
  
  CONCLUSIONS
  The VRR is an outcome predictor for local control in OPC and HPC patients treated with IMRT. Those with large tumor volumes or a VRR <0.5 should be considered for a salvage operation or a dose-escalation scheme.
authors.affiliation: Department of Radiation Oncology, China Medical University, Taichung, Taiwan.
authors.forename: Shih-Neng
authors.initials: SN
authors.lastname: Yang
authors.forename: Chih-Ying
authors.initials: CY
authors.lastname: Liao
authors.forename: Shang-Wen
authors.initials: SW
authors.lastname: Chen
authors.forename: Ji-An
authors.initials: JA
authors.lastname: Liang
authors.forename: Ming-Hsui
authors.initials: MH
authors.lastname: Tsai
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Hua
authors.forename: Fang-Jen
authors.initials: FJ
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden / Q000528:radiation effects*