The Esophagus
To understand esophageal cancer, you must first look at the esophagus--a 10 to 13-inch long tube that carries food and liquid down the throat and into the stomach. The walls of the esophagus have several layers. The mucosa layer is the one that lines the inside of your throat and esophagus. The layer beneath that is the submucosa. Beneath the submucosa is a thick layer of muscle band called the muscularis propria. And finally, the outermost layer is the adventitia, formed by connective tissue.
Cancer
Throughout most of your life, every cell in your body will divide, grow, and die. New cells will replace old ones, and the circle of life goes on. However, in patients with cancer, the cell doesn't die, but instead spawns new, abnormal cells. These abnormal cells do something that most other cells can't--invade other tissues.
Inside every cell is DNA. Normally, when a cell spawns another cell with damaged DNA, the damaged cell dies off. But since cancer cells don't die, they carry damaged DNA and gather in the body. This is why cancers often form tumors. Some types of cancer however, will not form tumors. Like leukemia, for instance. This is because the damaged cells are actually being transported through the bloodstream instead of gathering in one specific place.
Squamos Cells
Within the mucosa layer, there are two parts: the epithelium and the lamina propria. The first one, epithelium, is on top of the lamina propria, making it the layer that lines the esophagus. This layer is composed of many cells called squamos cells.
The Two Types of Esophageal Cancer
According to the American Cancer Society, there are two basic types of esophageal cancer. The first is squamos cell carcinoma. Because the entire lining of the esophagus is covered with squamos cells, this type of cancer can occur anywhere within the length of the esophagus. It used to be the most common type of esophageal cancer, making up about 90 percent of reported cases. But that number has dropped. Today, it is less than 50 percent of reported cases.
The other type of esophageal cancer is adenocarcinomas. This happens when the outer lining of the esophagus (the mucosa layer) is replaced by tissue that's a lot like the lining of your intestine. This is often referred to as Barrett's Esophagus. When this happens, there are areas of your esophageal lining that are no longer covered in squamos cells, but lined instead with glandular cells. Barrett's Esophagus most often occurs in the lower esophagus, and therefore is the most common site of adenocarcinomas.
Causes of Esophageal Cancer
Smoking and drinking excessively can obviously lead to cancer. But some lesser known causes of esophageal cancer are: the human papilloma virus (or HPV), and achalasia, (a condition in which the muscles lose their ability to move food down the esophagus). People with HPV are at risk of esophageal cancer because the virus transforms proteins in the esophagus which help suppress tumors, which lead to a loss of defense against abnormally growing cells.
Another cause of esophageal cancer comes from the disease achalasia. This is a fairly rare disease when the afflicted person's lower esophagus loses muscular power to push food into the stomach. This happens because the Lower Esophageal Sphincter (or LES) fails to relax, creating a barrier between the esophagus and the stomach. If detected early enough, one can begin treatment and monitoring to help prevent esophageal cancer due to achalasia. If untreated however, "There is an increased chance of developing esophageal cancer . . . " according to the UCLA Center for Esophageal Disorders.
Tags: esophageal cancer, esophageal cancer, mucosa layer, abnormal cells, Barrett Esophagus, epithelium lamina, epithelium lamina propria
