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Types of Cancer > Gastrointestinal Cancers > Esophageal Cancer > Overview

Esophageal Cancer: The Basics

Ryan P. Smith, MD and Eric T. Shinohara, MD
Affiliation: The Abramson Cancer Center of the University of Pennsylvania
Last Modified: February 21, 2008

What is the esophagus?

The esophagus is a muscular tube which connects the mouth to the stomach. The wall of the esophagus is composed of a series of muscles that are responsible for peristalsis, or the muscular motion that eases the delivery of food into the stomach. The esophagus is lined with two layers of tissue known as the mucosa and submucosa, which are where most cancers of the esophagus develop. The esophagus is a long tube, with an average length of 25 cm. The throat (or pharynx) is continuous with the esophagus, and although the two are indistinguishable, the esophagus is thought to start a few centimeters below the thyroid cartilage (Adam's apple). The esophagus travels down through the chest, between the lungs. It then passes through a hole in the diaphragm to connect with the stomach. There is a ring of muscle, also known as the lower esophageal sphincter, between the stomach and esophagus which prevents food in stomach acid from going back up into the esophagus.

What is esophageal cancer?

The definition of a tumor is a mass of quickly and abnormally growing cells. Tumors can be either benign or malignant. Benign tumors have uncontrolled cell growth, but without any invasion into normal tissues and without any spread. A malignant tumor is called cancer when these tumor cells gain the propensity to invade tissues and spread locally as well as to distant parts of the body. In this sense, esophageal cancer occurs when cells in the lining of the esophagus grow uncontrollably and form tumors that can invade normal tissues and spread to other parts of the body.

Cancers are described by the types of cells from which they arise. The vast majority of esophageal cancers develop from the inner lining (mucosa) of the esophagus and not from the muscle or cartilage cells that make up the rest of the esophagus. The lining of the esophagus is somewhat unique as it changes as it goes from the throat to the stomach. In the upper (proximal) esophagus, the lining of the esophagus resembles the lining of the throat, made up of squamous cells. Hence, when cancers develop in this region, they are usually squamous cell carcinomas. In the lower (distal) esophagus, the more common type of cancer is called adenocarcinoma, which is what the cancer is called when it develops from a lining that contains glands.

In addition to invasive cancers, patients are sometimes diagnosed with precancerous lesions, called carcinoma-in-situ. These precancerous lesions can be seen prior to the development of either squamous cell carcinoma or adenocarcinoma. Carcinoma-in-situ occurs when the lining of the esophagus undergoes changes similar to cancerous changes without any invasion into the deeper tissues. Hence, while the cells themselves have cancer-like qualities, there is no risk of spread, as no invasion has occurred. Another type of lesion that is considered to be a precursor to cancer itself is called Barrett's esophagus, which is explained in depth below.

Am I at risk for esophageal cancer?

Esophageal cancer occurs in approximately 13,500 Americans per year, causing about 12,500 deaths. Most patients are diagnosed in their 50s or 60s, with approximately four times as many men diagnosed than women. This being said, there is a dichotomy of patients who develop esophageal cancer. In the past, the vast majority (