After diagnosis, your cancer specialist will carry out tests to stage the cancer. This will help doctors plan the most appropriate treatment for you. The stage of a cancer describes its size and whether it has spread beyond its original site.
http://www.macmillan.org.uk/information-and-support/oesophageal-gullet-cancer/treating/treatment-decisions/understanding-your-diagnosis/staging.html
Staging Oesophageal Cancer