title: Outcomes and prognostic factors for recurrence after high-dose proton beam therapy for centrally and peripherally located stage I non--small-cell lung cancer.
abstract: BACKGROUND
  This study was conducted to determine disease control rates and prognostic factors associated with recurrence of centrally and peripherally located stage I NSCLC treated using high-dose PBT.
  
  
  METHODS
  Seventy-four patients with 80 centrally or peripherally located stage I NSCLCs were treated with PBT. A protocol using 72.6 Gy (RBE) in 22 fractions was used for centrally located tumors, and 66 Gy (RBE) in 10 or 12 fractions was used for peripherally located tumors. Data were collected and control rates and prognostic factors for recurrence were evaluated retrospectively.
  
  
  RESULTS
  The median follow-up period was 31.0 months. The overall survival, disease-specific survival, and progression-free survival rates were 76.7%, 83.0%, and 58.6% at 3 years, respectively. Disease recurrence was noted in 30 patients and local recurrence of 11 tumors occurred. The 3-year local control rate was 86.2% for stage IA tumors and 67.0% for stage IB tumors. Radiation dose was identified as a significant prognostic factor for disease recurrence and local recurrence. Tumor diameter and age were only significantly associated with disease recurrence. The 3-year local control rate was 63.9% for centrally located tumors irradiated with 72.6 Gy (RBE) and 88.4% for peripherally located tumors irradiated with 66 Gy (RBE).
  
  
  CONCLUSIONS
  Radiation dose was shown to be the most significant prognostic factor for tumor control in stage I NSCLC treated using high-dose PBT. Tumor diameter was not significant for local control. Further evaluation of PBT for centrally located tumors is warranted.
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan. Electronic address: ayaek@pmrc.tsukuba.ac.jp.
authors.forename: Ayae
authors.initials: A
authors.lastname: Kanemoto
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Okumura
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizumoto
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Oshiro
authors.affiliation: Department of Respiratory Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kurishima
authors.affiliation: Department of Respiratory Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Homma
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hashimoto
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Ohkawa
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Numajiri
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Ohno
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Moritake
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsuboi
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Takeji
authors.initials: T
authors.lastname: Sakae
authors.affiliation: Proton Medical Research Center and Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D009367:Neoplasm Staging; D011379:Prognosis; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D012189:Retrospective Studies
keywords: Outcome; Prognostic factor for tumor control; Proton beam therapy; Radiation dose; Stage I lung cancer