Esophageal cancer is a cancerous, or malignant, tumour that starts in the cells of the esophagus. Malignant means that it can destroy and invade normal tissue and spread, or metastasize, to other parts of the body.
The esophagus is part of the digestive system. It is a hollow, muscular tube behind the windpipe and in front of the spine. It carries food and drink from the back of the mouth to the stomach. When you swallow, the muscles of the esophagus tighten to push food or drink down the tube and into the stomach.
Cells in the esophagus sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous, or benign, conditions such as cysts or esophageal webs and rings. They can also lead to non-cancerous tumours such as leiomyomas.
Changes to cells of the esophagus can also cause precancerous conditions. This means that the cells are not yet cancer but there is a higher chance these abnormal changes will become cancer. The most common precancerous condition of the esophagus is Barrett’s esophagus.
In some cases, changes to esophageal cells can cause cancer. Most often, esophageal cancer starts in glandular cells, which make mucus. These cells are in the inner layer of the esophagus called the submucosa. This type of esophageal cancer is called adenocarcinoma of the esophagus. Cancer can also start in flat, thin cells called squamous cells. These cells make up the mucosa, or inner lining of the esophagus. This type of cancer is called squamous cell carcinoma of the esophagus.
Rare types of esophageal cancer can also develop. These include gastrointestinal (GI) neuroendocrine tumour or carcinoma, small cell carcinoma and leiomyosarcoma.