title: Robotic stereotactic body radiation therapy for elderly medically inoperable early-stage non-small cell lung cancer.
abstract: BACKGROUND
  Stereotactic body radiation therapy (SBRT) is being increasingly applied in the treatment of non-small cell lung cancer (NSCLC) because of its high local efficacy. This study aims to examine survival outcomes in elderly patients with inoperable stage I NSCLC treated with SBRT.
  
  
  METHODS
  A total of 31 patients with single lesions treated with fractionated SBRT from 2008 to 2011 were retrospectively analyzed. A median prescribed dose of 48 Gy was delivered to the prescription isodose line, over a median of four treatments. The median biologically effective dose (BED) was 105.6 (range 37.50-180), and the median age was 73 (65-90 years). No patient received concurrent chemotherapy.
  
  
  RESULTS
  With a median follow up of 13 months (range, 4-40 months), the actuarial median overall survival (OS) and progression-free survival (PFS) were 32 months, and 19 months, respectively. The actuarial median local control (LC) time was not reached. The survival outcomes at median follow up of 13 months were 80%, 68%, and 70% for LC, PFS, and OS, respectively. Univariate analysis revealed a BED of >100 Gy was associated with improved LC rates (P= 0.02), while squamous cell histology predicted for worse LC outcome at median follow up time of 13 months (P= 0.04). Increased tumor volume was a worse prognostic indicator of both LC and OS outcomes (P< 0.05). Finally, female gender was a better prognostic factor for OS than male gender (P= 0.006). There were no prognostic indicators of PFS that reached statistical significance. No acute or subacute high-grade toxicities were documented.
  
  
  CONCLUSIONS
  SBRT is a safe, feasible, and effective treatment option for elderly patients with inoperable early stage NSCLC. BED, histology, and tumor size are predictors of local control, while tumor size and gender predict OS.
authors.affiliation: Department of Radiation Oncology, Georgetown University Hospital, Washington, DC, USA.
authors.forename: Sana D
authors.initials: SD
authors.lastname: Karam
authors.affiliation: Department of Radiation Oncology, Georgetown University Hospital, Washington, DC, USA.
authors.forename: Zachary D
authors.initials: ZD
authors.lastname: Horne
authors.affiliation: Department of Radiation Oncology, Georgetown University Hospital, Washington, DC, USA; Department of Radiation Oncology, Virginia Hospital Center, Arlington, VA, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hong
authors.affiliation: Department of Radiation Oncology, Georgetown University Hospital, Washington, DC, USA.
authors.forename: Nimrah
authors.initials: N
authors.lastname: Baig
authors.affiliation: Department of Radiation Oncology, Frederick Memorial Hospital, Frederick, MD, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Gagnon
authors.affiliation: Department of Radiation Oncology, Virginia Hospital Center, Arlington, VA, USA.
authors.forename: Don
authors.initials: D
authors.lastname: McRae
authors.affiliation: Department of Pulmonary/Critical Care Medicine, Virginia Hospital Center, Arlington, VA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Duhamel
authors.affiliation: Department of Radiation Oncology, Georgetown University Hospital, Washington, DC, USA; Department of Radiation Oncology, Virginia Hospital Center, Arlington, VA, USA.
authors.forename: Nadim M
authors.initials: NM
authors.lastname: Nasr
keywords: BED; CyberKnife; SABR; gender; histology