[en] Esophageal cancers are highly malignant tumours with often a poor prognosis, except for minimal lesions treated with surgery. Radiation therapy, or combined radiation and chemotherapy is the most used therapeutic modality, alone or before oesophagectomy. The delineation of target volumes is now more accurate owing the possibility to use routinely the new imaging techniques (mainly PET). The aim of this work is to precise the radio-anatomical particularities, the pattern of spread of esophageal cancer and the principles of 3D conformal radiotherapy illustrated with a clinical case. (authors)