Only patients, which respond to neoadjuvant therapy and in which a subsequent complete resection (R0) is possible, demonstrate a significant survival advantage compared to non-responders. Therefore, a sensitive response evaluation is of high clinical interest. Response evaluation by endoscopy, biopsy, endoluminal ultrasound or by CT scan showed unfavourable and overall nor reliable results. In recent studies, a accurate response prediction employing 18FDG-PET seems to be possible. Following neoadjuvant chemoradiation of esophageal cancer, a sensitive differentiation between responders and non-responders was possible in a retrospective study. In the beginning are investigations, to differentiate already after two weeks of therapy between both groups of patients.