title: Predictors of individual tumor local control after stereotactic radiosurgery for non-small cell lung cancer brain metastases.
abstract: OBJECTIVE
  To evaluate local control rates and predictors of individual tumor local control for brain metastases from non-small cell lung cancer (NSCLC) treated with stereotactic radiosurgery (SRS).
  
  
  METHODS
  Between June 1998 and May 2011, 401 brain metastases in 228 patients were treated with Gamma Knife single-fraction SRS. Local failure was defined as an increase in lesion size after SRS. Local control was estimated using the Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis. Receiver operating characteristic analysis was used to identify an optimal cutpoint for conformality index relative to local control. A P value <.05 was considered statistically significant.
  
  
  RESULTS
  Median age was 60 years (range, 27-84 years). There were 66 cerebellar metastases (16%) and 335 supratentorial metastases (84%). The median prescription dose was 20 Gy (range, 14-24 Gy). Median overall survival from time of SRS was 12.1 months. The estimated local control at 12 months was 74%. On multivariate analysis, cerebellar location (hazard ratio [HR] 1.94, P=.009), larger tumor volume (HR 1.09, P<.001), and lower conformality (HR 0.700, P=.044) were significant independent predictors of local failure. Conformality index cutpoints of 1.4-1.9 were predictive of local control, whereas a cutpoint of 1.75 was the most predictive (P=.001). The adjusted Kaplan-Meier 1-year local control for conformality index ≥ 1.75 was 84% versus 69% for conformality index <1.75, controlling for tumor volume and location. The 1-year adjusted local control for cerebellar lesions was 60%, compared with 77% for supratentorial lesions, controlling for tumor volume and conformality index.
  
  
  CONCLUSIONS
  Cerebellar tumor location, lower conformality index, and larger tumor volume were significant independent predictors of local failure after SRS for brain metastases from NSCLC. These results warrant further investigation in a prospective setting.
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California.
authors.forename: Adam A
authors.initials: AA
authors.lastname: Garsa
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Shahed N
authors.initials: SN
authors.lastname: Badiyan
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Todd
authors.initials: T
authors.lastname: DeWees
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Simpson
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Jiayi
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Drzymala
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California.
authors.forename: Igor J
authors.initials: IJ
authors.lastname: Barani
authors.affiliation: Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Dowling
authors.affiliation: Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Rich
authors.affiliation: Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Chicoine
authors.affiliation: Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Albert H
authors.initials: AH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Leuthardt
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri. Electronic address: crobinson@radonc.wustl.edu.
authors.forename: Clifford G
authors.initials: CG
authors.lastname: Robinson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000401:mortality / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D002528:Cerebellar Neoplasms / Q000473:pathology / Q000556:secondary / Q000601:surgery; D005260:Female; D006801:Humans; D008175:Lung Neoplasms; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D016634:Radiosurgery / Q000379:methods*; D047368:Tumor Burden; D055815:Young Adult