title: Impact of Preexisting Interstitial Lung Disease on Acute, Extensive Radiation Pneumonitis: Retrospective Analysis of Patients with Lung Cancer.
abstract: BACKGROUND
  This study investigated the clinical characteristics and predictive factors for developing acute extended radiation pneumonitis with a focus on the presence and radiological characteristics of preexisting interstitial lung disease.
  
  
  METHODS
  Of 1429 irradiations for lung cancer from May 2006 to August 2013, we reviewed 651 irradiations involving the lung field. The presence, compatibility with usual interstitial pneumonia, and occupying area of preexisting interstitial lung disease were retrospectively evaluated by pretreatment computed tomography. Cases of non-infectious, non-cardiogenic, acute respiratory failure with an extended bilateral shadow developing within 30 days after the last irradiation were defined as acute extended radiation pneumonitis.
  
  
  RESULTS
  Nine (1.4%) patients developed acute extended radiation pneumonitis a mean of 6.7 days after the last irradiation. Although preexisting interstitial lung disease was found in 13% of patients (84 patients), 78% of patients (7 patients) with acute extended radiation pneumonitis cases had preexisting interstitial lung disease, which resulted in incidences of acute extended radiation pneumonitis of 0.35 and 8.3% in patients without and with preexisting interstitial lung disease, respectively. Multivariate logistic analysis indicated that the presence of preexisting interstitial lung disease (odds ratio = 22.6; 95% confidence interval = 5.29-155; p < 0.001) and performance status (≥2; odds ratio = 4.22; 95% confidence interval = 1.06-20.8; p = 0.049) were significant predictive factors. Further analysis of the 84 patients with preexisting interstitial lung disease revealed that involvement of more than 10% of the lung field was the only independent predictive factor associated with the risk of acute extended radiation pneumonitis (odds ratio = 6.14; 95% confidence interval = 1.0-37.4); p = 0.038).
  
  
  CONCLUSIONS
  Pretreatment computed tomography evaluations of the presence of and area size occupied by preexisting interstitial lung disease should be assessed for safer irradiation of areas involving the lung field.
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ozawa
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Abe
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Omae
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kato
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Enomoto
authors.affiliation: Department of Radiation Oncology, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Takeaki
authors.initials: T
authors.lastname: Ishihara
authors.affiliation: Department of Clinical Pharmacology and Therapeutics, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Inui
authors.affiliation: Department of Radiation Oncology, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Department of Respiratory Medicine, Respiratory Disease Center, Seirei Mikatahara General Hospital, Hamamatsu, Japan.
authors.forename: Koshi
authors.initials: K
authors.lastname: Yokomura
authors.affiliation: Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Suda
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016015:Logistic Models; D017563:Lung Diseases, Interstitial / Q000150:complications* / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017564:Radiation Pneumonitis / Q000000981:diagnostic imaging / Q000209:etiology*; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed