Dosimetry analysis on radiation-induced acute esophagitis after three-dimensional conformal radiotherapy for non-small cell lung cancer

Objective To analyze the related factors with radiation-induced esophagitis after threedimensional conformal radiotherapy for non-small cell lung cancer (NSCLC) ,in order to explore the predictors for optimizing the treatment planning of NSCLC.Methods From Aug 2000 to Dec 2004,104 NSCLC patients received radiotherapy and were eligible for this study,45 cases squamous cell carcinoma,20 cases adenocarcinoma,33 cases carrying with cancer cells by test and 6 case with no definitive pathologic feature.46 patients were treated with three dimensional conformal radiotherapy(3DCRT) ,the other 58 patients conventional radiotherapy (CRT) before later-course 3DCRT.All the patients received the prescribed dose between 60-78 Gy and the median dose 66 Gy.The correlation of the variables were evaluated by Spearman relationship analysis.The morbidity of radiation-induced esophagitis was analyzed by X~2 test.The multivariate effect on radiation-induced esophagitis was statistically processed by Logistic regression model.Results In 104 patients,the morbidity of radiation- induced esophagitis was 46.2% ,including 32 cases at grade 1,15 cases at grade 2,1 case at grade 3.Univariate analysis showed the maximal and mean dose of esophagus,the volume of esophagus irradiated,the values of V_(40) ,V_(45),V_(50) ,V_(55),V_(60) ,LETT_(45),LETT_(50) ,LETT_(55),LETT_(60) for the esophagus were correlated with radiation-induced esophagitis.Logistic regression model showed that the maximum dose received by the esophagus was the independent factor of ≥2 grade radiation-induced esophagitis.Conclusions The maxmal dose of esophagus received might be the important factor of radiation-induced esophagitis. Key words: Non-small cell lung cancer;  Three dimensional conformal radiotherapy; Radiation-induced esophagitis; DVH