Esophageal cancer is a disease in which malignant (cancer) cells form in the tissues of the esophagus.

The esophagus is the hollow, muscular tube that moves food and liquid from the throat to the stomach. The wall of the esophagus is made up of several layers of tissue, including mucous membrane, muscle, and connective tissue. Esophageal cancer starts on the inside lining of the esophagus and spreads outward through the other layers as it grows.

The two most common forms of esophageal cancer are named for the type of cells that become malignant (cancerous):

• Squamous cell carcinoma: Cancer that forms in the thin, flat cells lining the inside of the esophagus. This cancer is most often found in the upper and middle part of the esophagus, but can occur anywhere along the esophagus. This is also called epidermoid carcinoma.
• Adenocarcinoma: Cancer that begins in glandular cells. Glandular cells in the lining of the esophagus produce and release fluids such as mucus. Adenocarcinomas usually form in the lower part of the esophagus, near the stomach.

Smoking, heavy alcohol use, and Barrett esophagus can increase the risk of esophageal cancer.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors include the following:

• Tobacco use.
• Heavy alcohol use.
• Barrett esophagus: A condition in which the cells lining the lower part of the esophagus have changed or been replaced with abnormal cells that could lead to cancer of the esophagus. Gastric reflux (heartburn) is the most common cause of Barrett esophagus.
• Older age.