title: Radiation-induced pulmonary injury: symptomatic versus subclinical endpoints.
abstract: OBJECTIVE
  To assess the relationship between radiation (RT)-induced pulmonary symptoms and subclinical changes in pulmonary functions tests (PFT) and radiographs.
  
  
  METHODS
  A total of 184 patients irradiated between 1992 and 1998 were prospectively evaluated for RT-induced pulmonary symptoms, changes in computed tomography (CT) density, reductions in single photon emission CT (SPECT) perfusion, and changes in pulmonary functions tests (forced expiratory volume in 1 s [FEV1] and diffusion capacity to carbon monoxide [DLCO]). Comparisons between the evaluable patients with (N=34) and without (N=106) RT-induced pulmonary symptoms were made.
  
  
  RESULTS
  Within 6 months of RT, 80% of the RT-induced symptoms were noted. There was no association between the presence or absence of RT-induced pulmonary symptoms and the frequency of RT-induced radiographic changes (p=0.53), or in the dose-response curve for RT-induced reductions in regional perfusion. Overall, RT-induced changes in SPECT images were more commonly seen than increased density changes on CT (p<0.001). Most patients with pulmonary symptoms had relatively low pre-RT PFTs and experienced further declines following RT.
  
  
  CONCLUSIONS
  Regional radiographic changes in CT-defined tissue density or SPECT-defined tissue perfusion are similar in patients with and without RT-induced pulmonary symptoms because these endpoints do not consider the volume of lung affected. RT-induced pulmonary symptoms are better related to post-RT PFT because they are an assessment of whole lung function. Additional studies are necessary to better define models that can predict the degree of radiation-induced changes in whole lung function.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA. marks@radonc.duke.edu
authors.forename: L B
authors.initials: LB
authors.lastname: Marks
authors.forename: M
authors.initials: M
authors.lastname: Fan
authors.forename: R
authors.initials: R
authors.lastname: Clough
authors.forename: M
authors.initials: M
authors.lastname: Munley
authors.forename: G
authors.initials: G
authors.lastname: Bentel
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: R
authors.initials: R
authors.lastname: Jaszczak
authors.forename: D
authors.initials: D
authors.lastname: Hollis
authors.forename: M
authors.initials: M
authors.lastname: Anscher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D011878:Radiotherapy / Q000009:adverse effects*; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed