title: Comparison of Re-irradiation Outcomes for Charged Particle Radiotherapy and Robotic Stereotactic Radiotherapy Using CyberKnife for Recurrent Head and Neck Cancers: A Multi-institutional Matched-cohort Analysis.
abstract: To compare survival outcomes for charged particle radiotherapy (CP) and stereotactic body radiotherapy using CyberKnife (CK) in patients who had undergone re-irradiation for head and neck cancers.
  
  
  
  We conducted a retrospective multi-institutional matched-cohort analysis on 25 patients treated with CP and 25 matched patients treated with CK according to three prognostic factors (nasopharyngeal cancer or not, interval between initial radiotherapy and re-irradiation, and planning target volume).
  
  
  
  CP was used more often to treat non-squamous cell cancer ((non-SCC): 52% vs. 0%) with a higher prescribed dose (median=57.6 Gy(RBE)/16 fractions) than CK (32 Gy/5 fractions). The local control rate (LC) for patients treated with CP was 71.2% at 1 year and that for patients treated with CK was 63.8% (p=0.24). The 1-year overall survival (OS) rates were 67.1% for CP and 36.3% for CK (p=0.0002), respectively. Non-SCC patients showed better OS rates at 1 year than SCC patients. In the SCC sub-group analysis, the 1-year LC, OS rates were 65%, 58.3% in the CP group and 64%, 36.3% in the CK group (p=0.81, p=0.02), respectively. A total of 16 patients (32%) experienced grade 3 or worse toxicities (24% in CK and 40% in CP, p=0.36), including six grade 5 toxicities.
  
  
  
  CP produced higher survival rates than CK, treated more non-SCC patients and used a higher prescribed dose. On the other hand, severe toxicities occurred in both groups, which, however, require further investigation.
authors: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan hideya10@hotmail.com.|CyberKnife Center, Soseikai General Hospital, Kyoto, Japan.
authors: Hideya
authors: H
authors: Yamazaki
authors: Department of Radiology, Hyogo Ion Beam Medical Center, Hyogo, Japan.
authors: Yusuke
authors: Y
authors: Demizu
authors: Department of Radiology, Hyogo Ion Beam Medical Center, Hyogo, Japan.
authors: Tomoaki
authors: T
authors: Okimoto
authors: Radiotherapy Department, Fujimoto Hayasuzu Hospital, Miyazaki, Japan.
authors: Mikio
authors: M
authors: Ogita
authors: Department of Radiology, Japanese Red Cross Okayama Hospital, Okayama, Japan.
authors: Kengo
authors: K
authors: Himei
authors: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors: Satoaki
authors: S
authors: Nakamura
authors: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors: Gen
authors: G
authors: Suzuki
authors: Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan.
authors: Ken
authors: K
authors: Yoshida
authors: Department of Radiation Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan.
authors: Tadayuki
authors: T
authors: Kotsuma
authors: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Yasuo
authors: Y
authors: Yoshioka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011878:Radiotherapy / Q000295:instrumentation / Q000379:methods*; D012371:Robotics; D055815:Young Adult
keywords: Head and neck cancer; charged particle radiotherapy; re-irradiation; stereotactic radiotherapy