Purpose: To evaluate clinical and lung dose-volume histogram based factors as predictors of radiation pneumonitis (RP) in lung cancer patients (PTs) treated with thoracic irradiation. Methods and materials: Records of all lung cancer PTs irradiated at our Institution between 1994 and 2000 were retrospectively reviewed. Eighty-four PTs with small or non-small-cell lung cancer, irradiated at >40 Gy, with full 3D dosimetry data and a follow-up time of >6 months from start of treatment, were analysed for RP. Pneumonitis was scored on the basis of SWOG toxicity criteria and was considered a complication when grade≥II. The following clinical parameters were considered: gender, age, surgery, chemotherapy agents, presence of chronic obstructive pulmonary disease (COPD), performance status. Dosimetric factors including prescribed dose (D iso), presence of final conformal boost, mean lung dose (D mean), % of lung receiving ≥20, 25, 30, 35, 40, and 45 Gy (respectively V 20→V 45), and normal tissue complication probability (NTCP) values were analysed. DVHs data and NTCP values were collected for both lungs considered as a paired organ. Median and quartile values were taken as cut-off for statistical analysis. Factors that influenced RP were assessed by univariate (log-rank) and multivariate analyses (Cox hazard model). Results: There were 14 PTs (16.6%) who had ≥grade II pulmonary toxicity. In the entire population, the univariate analysis revealed that many dosimetric parameters (D iso, V 20, V 30, V 40, V 45) were significantly associated with RP. No significant correlation was found between the incidence of RP and D mean or NTCP values. Multivariate analysis revealed that the use of mitomycin (MMC) (P=0.005) and the presence of COPD (P=0.026) were the most important risk factor for RP. In the group without COPD (55 PTs, seven RP) a few dosimetric factors (D mean, V 20, V 45) and NTCP values (all models) were associated with RP in the univariate analysis (P≤0.06). According to the multivariate analysis, the use of MMC was independently associated with RP (P=0.007), while D mean approached statistical significance (P=0.082). Conclusions: In this study the use of mitomycin or the presence of COPD is associated with a higher risk of RP. In the entire population NTCP values were not significantly correlated with the incidence of RP. Mean lung dose shows a clear trend toward statistical significance in the patient group without COPD.
- Chronic obstructive pulmonary disease
- Dose-volume histogram
- Lung cancer
- Normal tissue complication probability
- Radiation pneumonitis
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging