title: Steep dose-response relationship for stage I non-small-cell lung cancer using hypofractionated high-dose irradiation by real-time tumor-tracking radiotherapy.
abstract: OBJECTIVE
  To investigate the clinical outcomes of patients with pathologically proven, peripherally located, Stage I non-small-cell lung cancer who had undergone stereotactic body radiotherapy using real-time tumor tracking radiotherapy during the developmental period.
  
  
  METHODS
  A total of 41 patients (25 with Stage T1 and 16 with Stage T2) were admitted to the study between February 2000 and June 2005. A 5-mm planning target volume margin was added to the clinical target volume determined with computed tomography at the end of the expiratory phase. The gating window ranged from +/-2 to 3 mm. The dose fractionation schedule was 40 or 48 Gy in four fractions within 1 week. The dose was prescribed at the center of the planning target volume, giving more than an 80% dose at the planning target volume periphery.
  
  
  RESULTS
  For 28 patients treated with 48 Gy in four fractions, the overall actuarial survival rate at 3 years was 82% for those with Stage IA and 32% for those with Stage IB. For patients treated with 40 Gy in four fractions within 1 week, the overall actuarial survival rate at 3 years was 50% for those with Stage IA and 0% for those with Stage IB. A significant difference was found in local control between those with Stage IB who received 40 Gy vs. 48 Gy (p = 0.0015) but not in those with Stage IA (p = 0.5811). No serious radiation morbidity was observed with either dose schedule.
  
  
  CONCLUSIONS
  The results of our study have shown that 48 Gy in four fractions within 1 week is a safe and effective treatment for peripherally located, Stage IA non-small-cell lung cancer. A steep dose-response curve between 40 and 48 Gy using a daily dose of 12 Gy delivered within 1 week was identified for Stage IB non-small-cell lung cancer in stereotactic body radiotherapy using real-time tumor tracking radiotherapy.
authors.affiliation: Department of Radiation Medicine, Hokkaido University School of Medicine, Sapporo, Japan. oni@radi.med.hokudai.ac.jp
authors.forename: Rikiya
authors.initials: R
authors.lastname: Onimaru
authors.forename: Masaharu
authors.initials: M
authors.lastname: Fujino
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Yuya
authors.initials: Y
authors.lastname: Onodera
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taguchi
authors.forename: Norio
authors.initials: N
authors.lastname: Katoh
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Hommura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Oizumi
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017564:Radiation Pneumonitis / Q000209:etiology; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods; D012044:Regression Analysis