title: Hypofractionated stereotactic radiotherapy using CyberKnife as a boost treatment for head and neck cancer, a multi-institutional survey: impact of planning target volume.
abstract: OBJECTIVE
  To evaluate the role of hypofractionated stereotactic radiotherapy (hSRT) as a boost treatment for head and neck cancer.
  
  
  METHODS
  We conducted a multi-institutional retrospective review for the outcome of boost irradiation using CyberKnife for head and neck cancer patients from the charts of four Institutes. Twenty-five patients were treated with hSRT boost for primary site with a median follow-up of 28 months. Treatment sites were 11 nasopharynx, 7 oropharynx, one hypopharynx, 3 nasal cavity or paranasal sinus and three oral cancers. All patients underwent preceding conventional radiotherapy of 35 to 72 Gy (median, 50 Gy) in 1.2- to 2 Gy-fractions. The dose and fractionation scheme of the Cyberknife SRT boost was individualized and the prescribed dose ranged from 12 Gy to 35 Gy in 1 to 5 fractions (median, 15 Gy in 3 fractions).
  
  
  RESULTS
  There were 18 complete responses, 6 partial responses and one progressive disease, resulting in 96% (24/25) response rate. Local control (LC) rates at 2- and 5-years were 89% and 71%, respectively. Progression-free survival (PFS) and overall survival (OS) at 2- and 5-years were 70%/ 83% and 70%/ 70%, respectively. Planning target volume (PTV) at boost treatment planning and initial response were predisposing factors for PFS and OS. Patients with PTV ≤ 20 cm(3) showed better PFS (92%) and OS (100%) than those with a PTV > 20 cm(3) (PFS, 61% and OS, 47%). Good initial response predicts better outcome in LC, PFS and OS.
  
  
  CONCLUSIONS
  The results of the present study showed potential benefits of the CyberKnife hSRT boost. Smaller PTV and good initial response predict good outcome.
authors.affiliation: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan CyberKnife Center, Soseikai General Hospital, Kyoto, Japan hideya10@hotmail.com.
authors.forename: Hideya
authors.initials: H
authors.lastname: Yamazaki
authors.affiliation: Radiotherapy Department, Fujimoto Hayasuzu Hospital, Miyazaki, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Ogita
authors.affiliation: Department of Radiology, Japanese Red cross Okayama Hospital, Okayama, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Himei
authors.affiliation: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Satoaki
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan.
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Kotsuma
authors.affiliation: Department of Radiation Oncology, NTT West Japan Osaka Hospital, Osaka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Sungjae
authors.initials: S
authors.lastname: Baek
authors.affiliation: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan CyberKnife Center, Soseikai General Hospital, Kyoto, Japan Radiotherapy Department, Fujimoto Hayasuzu Hospital, Miyazaki, Japan Department of Radiology, Japanese Red cross Okayama Hospital, Okayama, Japan Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan Department of Radiation Oncology, NTT West Japan Osaka Hospital, Osaka, Japan Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshioka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted; D016896:Treatment Outcome; D055815:Young Adult
keywords: CyberKnife; Head and neck cancer; boost therapy; stereotactic radiotherapy