Cancer starts when cells in the body change (mutate) and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them and die when your body doesn't need them any longer.

Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass. This is called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby areas. They can even spread to other parts of the body (metastasize).

Esophageal cancer is cancer that starts in the cells that make up the lining of your esophagus.

The esophagus is a tube that's part of the digestive tract. It carries food and liquid from your throat to your stomach. In adults, it's about 10 to 13 inches (25 to 33 centimeters) long. The esophagus is located behind the windpipe (trachea) and in front of your spine.

When you swallow, the esophagus tightens and relaxes. This causes “waves” along the tube. This motion moves food down into your stomach. Glands in the esophagus make mucus to keep the lining moist. This makes swallowing easier.

The wall of the esophagus has many layers that include mucosa, connective tissue, and muscle. The layer that lines the esophagus is called the mucosa. Its innermost epithelial lining is made up mainly of thin, flat cells. They are called squamous cells.

If stomach acid backs up into the lower part of the esophagus (acid reflux) over a long time, the squamous cells can be replaced by glandular cells. These cells make mucus and other fluids to try to protect the lower part of the esophagus. This change is called Barrett's esophagus.

The lower end of the esophagus connects to the stomach at the gastroesophageal junction (GEJ).

There are two main types of esophageal cancer:

• Adenocarcinoma. These are cancers that start in glandular cells. In the U.S. and other North American Western countries, most esophageal cancers are adenocarcinomas. These cancers normally start in the lower third of the esophagus where gland cells have replaced squamous cells. (This is what happens in Barrett's esophagus.)
• Squamous cell carcinoma. These cancers start in squamous cells. This type of cancer can start anywhere along the esophagus.

There are other types of esophageal cancer, but they are very rare.

Adenocarcinoma of the esophagus often starts in people with Barrett's esophagus. Still, most people with Barrett's esophagus never get esophageal cancer.

Over time, the gland cells that replace the squamous cells can develop dysplasia. This is when glandular cells start to look abnormal and grow in an abnormal way. Esophageal dysplasia is a precancer. If not treated, over time these cells can become cancer.

Both types of esophageal cancer start in the inner lining of the esophagus. As these cancers grow, they often narrow the opening in the center of the esophagus. (This opening is called the lumen.) This can cause problems with swallowing.

The cancer can also grow outward, through the layers of the esophagus to nearby tissues. These include nearby lymph nodes and the windpipe. Once the cancer has grown outside the esophagus, it can also spread to other parts of your body. It may spread to other organs, like your spine, liver, or lungs.

If you have questions about esophageal cancer, talk with your doctor. They can help you understand more about this cancer.