Margriet Kwint

Chapter 6 114 Purpose The purpose of this study is to investigate the dose-effect-relation between acute esophageal toxicity (AET) and dose-volume-parameters of the esophagus after Intensity Modulated Radiotherapy (IMRT) and concurrent chemotherapy for Non- Small Cell Lung Cancer (NSCLC) patients. Methods and materials One hundred thirty nine inoperable NSCLC patients treated with IMRT and concurrent chemotherapy were prospectively analyzed. The fractionation scheme was 24 x 2.75 Gy. All patients received concurrent a daily dose Cisplatin (6 mg/m²). Maximum AET was scored according to CTC 3.0. Dose-volume-parameters V5 to V70, D mean and D max of the esophagus were calculated. A logistic regression analysis was performed to analyze the dose-effect relation between these parameters and grade ≥2 and grade ≥3 AET. The outcome was compared to the clinically used esophagus V35 prediction model for grade ≥2 after radical 3D conformal radiotherapy (3DCRT) treatment. Results In our patient group 9% did not develop AET, 31% developed grade 1, 38% grade 2 and 22% grade 3 AET. The incidence of grade 2 and 3 AET was not different compared to patients treated with CCRT using 3DCRT. The V50 turned out to be the most significant dosimetric predictor for grade ≥3 AET (p=0.012). The derived V50-model was shown to predict grade ≥2 significantly better compared to the clinical V35-model (p<0.001). Conclusions For NSCLC patients treated with IMRT and concurrent chemotherapy, the V50 was identified as most accurate predictor of grade ≥3 AET. There is no difference in the incidence of grade ≥2 AET between 3DCRT and IMRT in patients treated with concurrent chemoradiotherapy.