Cancer is a disease in which cells grow in an abnormal way. Normally, the cells divide in a controlled manner. If cells keep dividing when new cells are not needed, a mass of tissue called a tumor forms.
A tumor can be benign or malignant. A benign tumor is not cancer and will not spread to other parts of the body. A malignant tumor is cancer. Cancer cells invade and damage tissue around them. They can also enter the lymph and blood streams, spreading to other parts of the body. Esophageal cancer is the development of malignant cells in the esophagus.
The esophagus is a muscular tube about 12 inches long that connects the throat to the stomach. It plays an important role in moving food downward into the stomach. Chewed food is formed into a small mass called a bolus. Once the bolus is swallowed, it is propelled down the esophagus and into the stomach by a series of coordinated and rhythmic muscular contractions.
The esophagus has 2 muscular rings called the upper and lower esophageal sphincters. The upper esophageal sphincter is controlled by swallowing, which allows food into the tube. The lower esophageal sphincter (LES) opens to allow food into the stomach. Once it passes through, the LES closes to help keep food and stomach acids inside the stomach during digestion.
Cell death and cell growth are a normal process in the body to replace old or damaged cells. The inside lining of the esophagus is an active area of the body that may have a high rate of cell turnover. Irritants introduced to the esophagus can increase inflammation and the rate of cell turnover. This turnover increases the risk of cellular mutations that can lead to uncontrolled growth. Irritants include stomach acid, alcohol, tobacco, and certain foods. Chronic digestive conditions, such as gastroesophageal reflux disease (GERD), also contribute to irritation.
Esophageal cancer tumors can cause blockages in the esophagus, which makes it difficult to swallow food. If the tumor grows beyond the esophageal layers, the cancer can penetrate nearby structures, such as the spine, trachea (the tube that carries air from the throat to the lungs), or the aorta (the body's largest artery). The cancer can cause damage to these structures and interfere with their function. It can also spread to lymph nodes or blood vessels, which can carry cancer cells to other areas of the body. The most common sites for metastatic esophageal cancer are the lungs, liver, kidney, and bones.
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