Contralateral esophageal sparing technique in definitive radiotherapy for non-small cell lung cancer: dosimetric parameters and normal tissue complication probability modeling.

Abstract

The purpose of this study was to assess the benefit of the contralateral esophageal sparing technique (CEST) in definitive radiotherapy of non-small cell lung cancer (NSCLC). We retrospectively reviewed radiation plans for 13 patients who underwent definitive chemoradiation for locally advanced NSCLC. Alternative plans were prepared with the use of CEST, with an additional margin of 5 mm from planning treatment volume (PTV). Normal tissue complication probability (NTCP) analyses for the esophagus and tumor control probability (TCP) for the PTV were performed for original and CEST plans using the equivalent uniform dose (EUD)-based mathematical model. In all cases, the CEST plan allowed for the reduction of esophageal dose, with a mean of 3.8 Gy (range, 0.7 to 8.7 Gy). The mean reductions of V40 and V60 to the esophagus were 6.4 Gy (range, 2.1 to 17.2 Gy) and 1.9 Gy (range, 3.4 to 10.0 Gy), respectively. There was no substantial decrease in the maximal dose to the esophagus. Reduction of NTCP was achieved for all patients (range, 5-73%), and TCP was not affected (-1.8 to +6.7%). The application of CEST in definitive radiotherapy of locally advanced NSCLC allows for reducing selected dosimetric parameters to the esophagus without compromising TCP.