Growths in the esophagus can be benign or malignant
The smooth inner wall may have an abnormal rough area, an area of tiny bumps, or a tumor. Benign growths are not as harmful as malignant growths:
Esophageal cancer begins in cells in the inner layer of the esophagus
Over time, the cancer may invade more deeply into the esophagus and nearby tissues. Cancer cells can spread by breaking away from the original tumor. They may enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues. The spread of cancer cells is called metastasis (or metastasize).
See the Staging section for information about esophageal cancer that has spread.Information provided by http://www.cancer.gov/cancertopics/wyntk/esophagus.pdf