The stages of esophageal cancer are indicated by Roman numerals that range from 0 to IV, with the lowest stages indicating that the cancer is small and affects only the superficial layers of your esophagus. By stage IV, the cancer is considered advanced and has spread to other areas of the body.
https://www.mayoclinic.org/diseases-conditions/esophageal-cancer/diagnosis-treatment/drc-20356090

