Clinical risk factors of radiation pneumonitis after 3D conformal radiotherapy for lung cancer

Radiotherapy (RT) was an important tool in treating lung cancer. Radiation pneumonitits (RP) was one of the major side effects after thoracic RT. RP may further offset the potential survival benefit of concurrent chemoradiotherapy (CCRT). We reported our clinical results of 3D conformal radiotherapy (3DCRT) with focus on risk factors of RP. From Apr 2003 to Mar 2004, medical records of consecutive patients with lung cancer receiving thoracic RT with detailed lung dose data (V20 and mean lung dose (MLD)) and at least 3 months' follow up (FU) were reviewed and constituted the study group. Common toxicity criteria III were used for grading of RP. Univariate analysis by Fisher's exact test was used for analysis of risk factors . Thirty-five patients fulfilled our criteria. Most of them had stage III non-small cell lung cancer (NSCLC) (19/35) and received CCRT (18/35). The median RT dose was 54Gy. The median V20 and MLD were 22.7% and 14.3Gy. Grade II RP was noted in three patients only after median follow up of 6 months. Among patient, tumor, treatment, and RT related factors, MLD (≧ 16Gy) was found to be a significant risk factor (risk: 3/12 vs 0/23, p=0.03). V20(≧ 25%) and tumor location (middle/lower lobes) were also found to be risk factors with borderline statistical significance (p=0.056) MLD, V20 and the location of primary tumor were possible clinical predictors of radiation pneumonitis after 3D conformal radiotherapy for lung cancer. Further work up was needed to clarify other possible risk factors.