title: Pulmonary function following high-dose radiotherapy of non-small-cell lung cancer.
abstract: OBJECTIVE
  To study changes of pulmonary function tests (PFTs) after radiotherapy (RT) of non-small-cell lung cancer (NSCLC) in relation to radiation dose, tumor regression, and changes in lung perfusion.
  
  
  METHODS
  Eighty-two patients with inoperable NSCLC were evaluated with PFTs (forced expiratory volume in 1 s [FEV(1)] and diffusion capacity [T(L,COc)]), a computed tomography (CT) scan of the chest, and a single photon emission CT (SPECT) lung perfusion scan, before and 3-4 months after RT. The reductions of PFTs and tumor volume were calculated. The lung perfusion was measured from pre- and post-RT SPECT scans, and the difference was defined as the measured perfusion reduction (MPR). In addition, the perfusion post-RT was estimated from the dose distribution using a dose-effect relation for regional lung perfusion, and compared with the pre-RT lung perfusion to obtain the predicted perfusion reduction (PPR). The difference between the actually measured and the PPR was defined as reperfusion. The mean lung dose (MLD) was computed and weighted with the pre-RT perfusion, resulting in the mean perfusion-weighted lung dose (MpLD). Changes of PFTs were evaluated in relation to tumor dose, MLD, MpLD, tumor regression, and parameters related to perfusion changes.
  
  
  RESULTS
  In a multivariate analysis, the total tumor dose and MLD were not associated with reductions of PFTs. Tumor regression resulted in a significant improvement of FEV(1) (p = 0.02), but was associated with a reduction of T(L,COc) (p = 0.05). The MpLD and the PPR showed a significant (p = 0.01 to 0.04) but low correlation (r = 0.24 to 0.31) with the reduction of both PFTs. The other parameters for perfusion changes, the MPR and reperfusion were not correlated with changes in PFTs.
  
  
  CONCLUSIONS
  The perfusion-related dose variables, the MpLD or the PPR, are the best parameters to estimate PFTs after RT. Tumor regression is associated with an improvement of FEV(1) and a decline of T(L,COc). Reperfusion was not associated with an improvement of global pulmonary function.
authors.affiliation: Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
authors.forename: Katrien
authors.initials: K
authors.lastname: De Jaeger
authors.forename: Yvette
authors.initials: Y
authors.lastname: Seppenwoolde
authors.forename: Liesbeth J
authors.initials: LJ
authors.lastname: Boersma
authors.forename: Sara H
authors.initials: SH
authors.lastname: Muller
authors.forename: Paul
authors.initials: P
authors.lastname: Baas
authors.forename: José S A
authors.initials: JS
authors.lastname: Belderbos
authors.forename: Joos V
authors.initials: JV
authors.lastname: Lebesque
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000503:physiopathology / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D021621:Imaging, Three-Dimensional; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000528:radiation effects; D008175:Lung Neoplasms / Q000503:physiopathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D017564:Radiation Pneumonitis / Q000209:etiology / Q000503:physiopathology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy / Q000009:adverse effects; D012129:Respiratory Function Tests; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014692:Ventilation-Perfusion Ratio