Predictors of Grade ≥ 2 and Grade ≥ 3 Radiation Pneumonitis in Patients with Locally Advanced Non-Small Cell Lung Cancer Treated with Three-Dimensional Conformal Radiotherapy

Grade >= 3 radiation pneumonitis (RP) is generally severe and life-threatening. Predictors of grade >= 2 are usually used for grade >= 3 RP prediction, but it is unclear whether these predictors are appropriate. In this study, predictors of grade >= 2 and grade >= 3 RP were investigated separately. The increased risk of severe RP in elderly patients compared with younger patients was also evaluated. Material and methods. A total of 176 consecutive patients with locally advanced non-small cell lung cancer were followed up prospectively after three-dimensional conformal radiotherapy. RP was graded according to Common Terminology Criteria for Adverse Events version 3.0. Results. Mean lung dose (MLD), mean heart dose, ratio of planning target volume to total lung volume (PTV/Lung), and dose-volume histogram comprehensive value of both heart and lung were associated with both grade >= 2 and grade >= 3 RP in univariate analysis. In multivariate logistic regression analysis, age and MLD were predictors of both grade >= 2 RP and grade >= 3 RP; receipt of chemotherapy predicted grade >= 3 RP only; and sex and PTV/Lung predicted grade >= 2 RP only. Among patients who developed high-grade RP, MLD and PTV/Lung were significantly lower in patients aged >= 70 years than in younger patients (p < 0.05 for both comparisons). Conclusions. The predictors were not completely consistent between grade >= 2 RP and grade >= 3 RP. Elderly patients had a higher risk of severe RIP than younger patients did, possibly due to lower tolerance of radiation to the lung.