Functional Imaging to Identify Radiosensitive Esophageal Cancer - a Biomarker Validation Study

Inclusion Criteria: * patients with squamous cell, undifferentiated or adenocarcinoma of the esophagus, UICC stage II-IVA (maximum T4a) * ECOG performace status 0-2 * Complete clinical staging, including, esophagogastroscopy, EUS, CT neck/thorax/abdomen and adequate pulmonary function. * Adequate hematological, renal, hepatic and pulmonary functions defined as: granulocytes ≥ 1.5 x 109/l platelets ≥ 100 x 109/l total bilirubin ≤ 1.5 x upper normal limit creatinine ≤ 120 μmol/L FEV1 ≥ 1.5 L * Written, voluntary informed consent * Willingness to perform effective contraceptive practices during treatment for patients with childbearing potential Exclusion Criteria: * Evidence of distant metastases (cM1) * Prior high-dose radiotherapy to the thorax or abdomen * Primary tumor cT4b * history or concurrent malignancy as judged by the treating physician. This is only an exclusion criterion if the other malignancy is considered the oncological potentially leading cause of death compared to the esophageal cancer.