Radiation pneumonitis develops within hours or days of lung IR and is accompanied by increased capillary permeability, leukocyte infiltration, and release of cytokines, such as transforming growth factor β (TGF-β), interleukin 6 (IL-6), tumor necrosis factor alpha, and interleukin-1 beta (IL-1β). This evidence concerns the gene IL1B and radiation pneumonitis.