Risk factors for severe radiation pneumonitis in lung cancer.

BACKGROUND

Risk factors for severe radiation pneumonitis, which often spreads beyond treatment portals and may even be bilateral, have not been fully investigated. The purpose of this study was to identify important factors associated with severe radiation pneumonitis.

METHODS

111 cases of primary lung cancer, treated with radiotherapy or chemoradiotherapy, were retrospectively analyzed.

RESULTS

Severe radiation pneumonitis occurred in 17 cases (15.3%). The ratio of interstitial change in lungs before radiotherapy and radiotherapy to the contralateral mediastinum with > 40 Gy in the radiation pneumonitis group (RP group) was significantly higher than in patients without radiation pneumonitis (control group) (47.1% vs 5.3%; P < 0.001 and 58.8% vs 27.7%; P = 0.037, respectively). Using logistic regression analysis, interstitial changes before radiotherapy and radiotherapy to the contralateral mediastinum of > 40 Gy were significant risk factors associated with severe radiation pneumonitis.

CONCLUSIONS

These data suggest that pre-existing interstitial changes detected by chest radiography or computed tomography and radiotherapy to the contralateral mediastinum (> 40 Gy) may predict the development of severe radiation pneumonitis.