[Gross tumor volume and clinical target volume: esophageal tumors]

The oesophagus is divided into four regions: cervical oesophagus, and intrathoracic oesophagus with an upper, mid- and lower thoracic portion. Cancer may occur on each of these regions. Computed tomography of the thorax and superior abdomen and endoscopic ultrasound are necessary for reliable staging. CT simulation allows accurate definition of tumour volume. GTV includes tumour volume and regional lymph nodes. CTV encompasses GTV plus a safety margin and lymph node areas considered to harbour potential microscopic disease. The extent of prophylactic lymph node irradiation depends on the anatomic location of the primary tumour.