The incidence of radiation pneumonitis in the low-SOD group was significantly higher than that in the high-SOD group (53.85% versus 46.15%, p=0.032), while two patients in the low-SOD group (3.08%) and one patient in the high-SOD group (1.54%) experienced grade 3 radiation pneumonitis. This evidence concerns the gene SOD1 and radiation pneumonitis.