title: Clinical outcomes of single or oligo-fractionated stereotactic radiotherapy for head and neck tumors using micromultileaf collimator-based dynamic conformal arcs.
abstract: OBJECTIVE
  To assess the clinical outcomes of single or oligo-fractionated stereotactic radiotherapy (SRT) using dynamic conformal arcs (DCA) for head and neck tumors (HNTs).
  
  
  METHODS
  Thirty-four consecutive patients with 35 lesions treated between 2005 and 2009 were retrospectively evaluated, of whom 85.7 % had recurrent or metastatic disease, and 45.7 and 34.3 % had previous radiotherapy and surgery, respectively. The median SRT dose was 22.3 Gy (11.2-32.8) in 2-4 fractions with a median interval of 7 days and 10.4 Gy (9.2-12.4) in one fraction. SRT was combined with upfront conventionally fractionated RT in 48.6 % of patients.
  
  
  RESULTS
  The median follow-up periods were 18.4 months (2-84.1) for the entire cohort and 49.6 months for the survivors. The 1- and 2-year local control (LC) rates were 84.3 and 70.5 %, with the 1- and 2-year overall survival (OS) rates of 78.6 and 51.6 %. LC was significantly better for tumor volumes <25.6 cm(3) (p = 0.001). OS was significantly longer in patients without any disease outside the SRT site (p < 0.001), whereas LC after the SRT did not affect the OS. Late adverse events occurred in 9 patients, including cranial nerve (CN) injury (grade 3/4) in 2, brain radionecrosis in 5 (grade 1), and fatal bleeding in 2 patients harboring uncontrolled lesions abutting the carotid artery.
  
  
  CONCLUSIONS
  DCA-based SRT can confer relatively long-term LC with acceptable toxicity in selected patients with HNTs. The patients with CN involvement or tumor volume ≥25.6 cm(3) were deemed unsuitable for this treatment regimen.
authors.affiliation: Department of Radiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. ohtakara@gifu-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ohtakara
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayashi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Mizuta
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Aoki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ando
authors.forename: Sunaho
authors.initials: S
authors.lastname: Okada
authors.forename: Yatsuji
authors.initials: Y
authors.lastname: Ito
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hoshi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003872:Dermatitis / Q000209:etiology; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D052016:Mucositis / Q000209:etiology; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000209:etiology / Q000601:surgery; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome