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 RP than younger patients did, possibly due to lower tolerance of radiation to the lung.