Predictors of radiation-induced lung toxicities in patients with thoracic middle and lower esophageal cancer treated with three-dimensional conformal radiotherapy

Objective: To evaluate the clinical and dosimetric predictors of acute and late lung toxicity in patients with thoracic middle and lower esophageal cancer treated with three-dimensional conformal radiotherapy(3DCRT). Methods: Sixty-five patients with the said esophageal cancer treated by 3DCRT were included in this study. Clinical symptoms, chest X-ray, CT and HRCT scan were used to detect the acute radiation pneumonitis and the late radiation lung toxicities. The clinical factors and treatment parameters were collected and coded. All factors correlating with acute and late lung toxicity were analyzed. Results: 1. Univariate analysis showed that the primitive tumor length, prescription dose, lung V5-V25, lung Dmean, esophageal PTVD90, esophageal PTVV50 and radiation fields were factors causing acute radiation pneumonitis. The magnitude of these values was significantly different between patients with and without radiation pneumonitis. The primary tumor length, lung V5-V40, lung Dmean and combined chemotherapy had a significant relationship with the late radiation lung toxicities. The magnitude of these values were also significantly different in patients with and without late radiation lung toxicities. 2. Binary Logistic regression analysis showed that lung V25, the primary tumor length and the radiation fields were the independent risk factors of acute radiation pneumonitis. Lung V30 and combined chemotherapy were independent risk factors of late radiation lung toxicity. 3. There were no relation between acute radiation pneumonitis or late radiation lung toxicities. 4. There were no relation between the survival rate and acute radiation pneumonitis or late radiation lung toxicities. Conclusions: In thoracic middle and lower esophageal cancer patients treated with 3DCRT, lung V25, primitive tumor length and radiation fields were significantly associated with a risk of acute radiation pneumonitis. Lung V30 and combined chemotherapy were independent risk factors of late radiation lung toxicities. (authors)