title: Imaging features associated with disease progression after stereotactic ablative radiotherapy for stage I non-small-cell lung cancer.
abstract: BACKGROUND
  The aim of this study was to identify imaging-based predictors of progression in patients treated with SABR for stage I NSCLC.
  
  
  METHODS
  Between March 2003 and December 2012, 117 patients with stage I NSCLC meeting our study criteria were treated with SABR at Stanford University. Median follow-up was 17 months (range, 3-74 months) for all patients and 19 months for living patients (range, 3-74 months). Tumors were classified according to whether or not they contacted the pleura adjacent to the chest wall or mediastinum (MP), according to their maximum dimension based on computed tomography scans, and, for 102 patients who had archived pretreatment fluorine-18 fluorodeoxyglucose positron-emission tomography scans, according to SUVmax.
  
  
  RESULTS
  Ten patients (9%) developed local progression, 17 (15%) developed regional progression, and 19 (16%) developed distant metastasis. Two-year freedom from local progression, freedom from regional progression, and freedom from distant metastasis (FFDM) were 88%, 83%, and 83%, respectively. Overall survival was 70% at 2 years. FFDM was significantly associated with MP contact, maximum tumor dimension, and SUVmax, and these variables could be combined into an exploratory prognostic index that identified patients at highest risk for developing metastases.
  
  
  CONCLUSIONS
  In our cohort, noninvasive, imaging-based features were associated with distant progression after SABR for early stage NSCLC. If validated, our prognostic index could allow identification of patients who might benefit from systemic therapy after SABR.
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.
authors.forename: David B
authors.initials: DB
authors.lastname: Shultz
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Trakul
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Abelson
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.
authors.forename: James D
authors.initials: JD
authors.lastname: Murphy
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA.
authors.forename: Quynh-Thu
authors.initials: QT
authors.lastname: Le
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA.
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA. Electronic address: mdiehn@gmail.com.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Diehn
mesh_terms: D055011:Ablation Techniques; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D003952:Diagnostic Imaging; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D016634:Radiosurgery; D016019:Survival Analysis
keywords: Early stage; FDG-PET; Prognostic; SABR; Stereotactic body radiation therapy (SBRT)