title: Patients with severe emphysema have a low risk of radiation pneumonitis following stereotactic body radiotherapy.
abstract: OBJECTIVE
  To evaluate the risk of radiation pneumonitis (RP) after stereotactic radiotherapy (SBRT) for patients presenting with severe pulmonary emphysema.
  
  
  METHODS
  This study included 40 patients with Stage I non-small-cell lung cancer who underwent SBRT, 75 Gy given in 30 fractions, at the Tokyo Medical University, Tokyo, Japan, between February 2010 and February 2013. The median age of the patients was 79 years (range, 49-90 years), and the male:female ratio was 24:16. There were 20 T1 and 20 T2 tumours. 17 patients had emphysema, 6 had slight interstitial changes on CT images and the remaining 17 had no underlying lung disease. The level of emphysema was classified into three groups according to the modified Goddard's criteria (severe: three patients, moderate: eight patients and mild: six patients). Changes in the irradiated lung following SBRT were evaluated by CT.
  
  
  RESULTS
  On CT images, RP was detected in 34 (85%) patients, and not in 6 (15%) patients, during a median observation period of 313 days. Of the six patients, three had severe emphysema and three had no underlying lung disease. Patients with severe emphysema had lower risk of RP than those with moderate emphysema (p = 0.01), mild emphysema (p = 0.04) and no underlying lung disease (p = 0.01).
  
  
  CONCLUSIONS
  Patients with severe emphysema had a low risk of RP following SBRT.
  
  
  CONCLUSIONS
  Little is known about the association between RP and pulmonary emphysema. Patients with severe emphysema had lower risk of RP than those with no underlying lung disease.
authors.affiliation: Department of Radiology, Tokyo Medical University Hospital, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ishijima
authors.forename: H
authors.initials: H
authors.lastname: Nakayama
authors.forename: T
authors.initials: T
authors.lastname: Itonaga
authors.forename: Y
authors.initials: Y
authors.lastname: Tajima
authors.forename: S
authors.initials: S
authors.lastname: Shiraishi
authors.forename: M
authors.initials: M
authors.lastname: Okubo
authors.forename: R
authors.initials: R
authors.lastname: Mikami
authors.forename: K
authors.initials: K
authors.lastname: Tokuuye
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000175:diagnosis* / Q000209:etiology; D017564:Radiation Pneumonitis / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed