title: The impact of tumor volume and radiotherapy dose on outcome in previously irradiated recurrent squamous cell carcinoma of the head and neck treated with stereotactic body radiation therapy.
abstract: OBJECTIVE
  To assess the effect of stereotactic body radiotherapy (SBRT) dose and tumor volume on outcomes in patients with recurrent, previously irradiated squamous cell carcinoma of the head and neck.
  
  
  METHODS
  A total of 96 patients with recurrent, previously irradiated squamous cell carcinoma of the head and neck were treated with SBRT using Cyberknife and Trilogy-intensity-modulated radiosurgery. Kaplan-Meier survival analyses were used to estimate locoregional control (LRC) and overall survival rates. Response was evaluated using positron emission tomography/computed tomography or computed tomography and detailed physical examination.
  
  
  RESULTS
  The median follow-up for all patients was 14 months (2-39 months). The median dose of prior radiation was 68.4 Gy (32-170 Gy). Patients were divided into 4 SBRT dose groups: I (15-28 Gy/n = 29), II (30-36 Gy/n = 22), III (40 Gy/n = 18), and IV (44-50 Gy/n = 27). The median gross tumor volume (GTV) was 24.3(3) cm (2.5-162 cm). For GTV ≤25 cm(3) (n = 50), complete response rates were 27.8%/30%/45.5%/45.5%, and for GTV >25 cm(3) (n = 46), complete response rates were 20%/25%/42.8%/50% for SBRT groups I-IV, respectively. The 1-/2-/3-year LRC rates for doses 40 to 50 Gy were 69.4%/57.8%/41.1%, respectively, whereas for 15 to 36 Gy, they were 51.9%/31.7%/15.9%, respectively (P = 0.02). The overall 1- and 2-year overall survival rates were 58.9% and 28.4%, respectively. Treatment was well tolerated with no grade 4/5 toxicities.
  
  
  CONCLUSIONS
  Dose escalation up to 50 Gy in 5 fractions is feasible with SBRT for recurrent head and neck squamous cell carcinoma. Higher SBRT doses were associated with significantly higher LRC rates. Large tumor volume required higher SBRT doses to achieve optimal response rates compared with smaller tumor volume.
authors.affiliation: Departments of Radiation Oncology, University of Pittsburgh Cancer Institute, PA, USA.
authors.forename: Jean-Claude M
authors.initials: JC
authors.lastname: Rwigema
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Heron
authors.forename: Robert L
authors.initials: RL
authors.lastname: Ferris
authors.forename: Regiane S
authors.initials: RS
authors.lastname: Andrade
authors.forename: Michael K
authors.initials: MK
authors.lastname: Gibson
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Cihat
authors.initials: C
authors.lastname: Ozhasoglu
authors.forename: Athanassios E
authors.initials: AE
authors.lastname: Argiris
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Grandis
authors.forename: Steven A
authors.initials: SA
authors.lastname: Burton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy*; D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy*; D049268:Positron-Emission Tomography; D016634:Radiosurgery; D012189:Retrospective Studies; D016879:Salvage Therapy; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden