Lung Size and the Risk of Radiation Pneumonitis

Purpose The purpose of this study was to identify patient populations treated for non-small cell lung cancer (NSCLC) who may be more at risk of radiation pneumonitis. Methods and Materials A total of 579 patients receiving fractionated 3D conformal or intensity modulated radiation therapy (IMRT) for NSCLC were included in the study. Statistical analysis was performed to search for cohorts of patients with higher incidences of radiation pneumonitis. In addition to conventional risk factors, total and spared lung volumes were analyzed. The Lyman-Kutcher-Burman (LKB) and cure models were then used to fit the incidence of radiation pneumonitis as a function of lung dose and other factors. Results Total lung volumes with a sparing of less than 1854 cc at 40 Gy were associated with a significantly higher incidence of radiation pneumonitis at 6 months (38% vs 12% for patients with larger volumes, P