title: Stereotactic body radiotherapy using gated radiotherapy with real-time tumor-tracking for stage I non-small cell lung cancer.
abstract: BACKGROUND
  To clarify the clinical outcomes of two dose schedule of stereotactic body radiotherapy (SBRT) for stage I non-small cell lung cancer (NSCLC) using a real-time tumor-tracking radiation therapy (RTRT) system in single institution.
  
  
  METHODS
  Using a superposition algorithm, we administered 48 Gy in 4 fractions at the isocenter in 2005-2006 and 40 Gy in 4 fractions to the 95% volume of PTV in 2007-2010 with a treatment period of 4 to 7 days. Target volume margins were fixed irrespective of the tumor amplitude.
  
  
  RESULTS
  In total, 109 patients (79 T1N0M0 and 30 T2N0M0). With a median follow-up period of 25 months (range, 4 to 72 months), the 5-year local control rate (LC) was 78% and the 5-year overall survival rate (OS) was 64%. Grade 2, 3, 4, and 5 radiation pneumonitis (RP) was experienced by 15 (13.8%), 3 (2.8%), 0, and 0 patients, respectively. The mean lung dose (MLD) and the volume of lung receiving 20 Gy (V20) were significantly higher in patients with RP Grade 2/3 than in those with RP Grade 0/1 (MLD p = 0.002, V20 p = 0.003). There was no correlation between larger maximum amplitude of marker movement and larger PTV (r = 0.137), MLD (r = 0.046), or V20 (r = 0.158).
  
  
  CONCLUSIONS
  SBRT using the RTRT system achieved LC and OS comparable to other SBRT studies with very low incidence of RP, which was consistent with the small MLD and V20 irrespective of tumor amplitude. For stage I NSCLC, SBRT using RTRT was suggested to be reliable and effective, especially for patients with large amplitude of tumor movement.
authors.affiliation: Department of Radiation Medicine, Hokkaido University Graduate School of Medicine, North 15 West 7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Inoue
authors.forename: Norio
authors.initials: N
authors.lastname: Katoh
authors.forename: Rikiya
authors.initials: R
authors.lastname: Onimaru
authors.forename: Shinichi
authors.initials: S
authors.lastname: Shimizu
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Suzuki
authors.forename: Jun
authors.initials: J
authors.lastname: Sakakibara-Konishi
authors.forename: Naofumi
authors.initials: N
authors.lastname: Shinagawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Oizumi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D003131:Combined Modality Therapy / Q000379:methods; D003199:Computer Systems; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden / Q000528:radiation effects