title: Prospective assessment of dosimetric/physiologic-based models for predicting radiation pneumonitis.
abstract: OBJECTIVE
  Clinical and 3D dosimetric parameters are associated with symptomatic radiation pneumonitis rates in retrospective studies. Such parameters include: mean lung dose (MLD), radiation (RT) dose to perfused lung (via SPECT), and pre-RT lung function. Based on prior publications, we defined pre-RT criteria hypothesized to be predictive for later development of pneumonitis. We herein prospectively test the predictive abilities of these dosimetric/functional parameters on 2 cohorts of patients from Duke and The Netherlands Cancer Institute (NKI).
  
  
  METHODS
  For the Duke cohort, 55 eligible patients treated between 1999 and 2005 on a prospective IRB-approved study to monitor RT-induced lung injury were analyzed. A similar group of patients treated at the NKI between 1996 and 2002 were identified. Patients believed to be at high and low risk for pneumonitis were defined based on: (1) MLD; (2) OpRP (sum of predicted perfusion reduction based on regional dose-response curve); and (3) pre-RT DLCO. All doses reflected tissue density heterogeneity. The rates of grade > or =2 pneumonitis in the "presumed" high and low risk groups were compared using Fisher's exact test.
  
  
  RESULTS
  In the Duke group, pneumonitis rates in patients prospectively deemed to be at "high" vs. "low" risk are 7 of 20 and 9 of 35, respectively; p = 0.33 one-tailed Fisher's. Similarly, comparable rates for the NKI group are 4 of 21 and 6 of 44, respectively, p = 0.41 one-tailed Fisher's.
  
  
  CONCLUSIONS
  The prospective model appears unable to accurately segregate patients into high vs. low risk groups. However, considered retrospectively, these data are consistent with prior studies suggesting that dosimetric (e.g., MLD) and functional (e.g., PFTs or SPECT) parameters are predictive for RT-induced pneumonitis. Additional work is needed to better identify, and prospectively assess, predictors of RT-induced lung injury.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Zafer
authors.initials: Z
authors.lastname: Kocak
authors.forename: Gerben R
authors.initials: GR
authors.lastname: Borst
authors.forename: Jing
authors.initials: J
authors.lastname: Zeng
authors.forename: Sumin
authors.initials: S
authors.lastname: Zhou
authors.forename: Donna R
authors.initials: DR
authors.lastname: Hollis
authors.forename: Junan
authors.initials: J
authors.lastname: Zhang
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Evans
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Folz
authors.forename: Terrence
authors.initials: T
authors.lastname: Wong
authors.forename: Daniel
authors.initials: D
authors.lastname: Kahn
authors.forename: Jose S A
authors.initials: JS
authors.lastname: Belderbos
authors.forename: Joos V
authors.initials: JV
authors.lastname: Lebesque
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011446:Prospective Studies; D012372:ROC Curve; D017564:Radiation Pneumonitis / Q000209:etiology*; D011879:Radiotherapy Dosage; D012129:Respiratory Function Tests; D018570:Risk Assessment