Patients with severe emphysema have a low risk of radiation pneumonitis following stereotactic body radiotherapy

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, 75Gy 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, RPwas 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 thosewithmoderate emphysema (p = 0.01), mild emphysema (p = 0.04) and no underlying lung disease (p = 0.01). Conclusion: Patients with severe emphysema had a low risk of RP following SBRT. Advances in knowledge: 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.