Esophageal cancer occurs in your esophagus, the long, hollow tube that connects your throat to your stomach.
Even though esophageal cancer can start and occur anywhere in the esophagus, it typically begins in the inner layer of the esophagus wall and moves outward.
Esophageal cancer: learn more
The esophagus sits in front of your spine and behind the trachea (your windpipe). Your esophagus is made up of four different parts, including the upper esophageal sphincter, the lumen, the gastroesophageal junction (GE) and the lower esophageal sphincter.
Located at the opening of the upper esophagus, the upper esophageal sphincter is a ring of muscle that allows food or liquid to pass through it.
Food and liquids that you swallow move to the inside of the esophagus, called the lumen, towards the stomach.
The gastroesophageal (GE) junction is the name of the connection point where the lower part of the esophagus meets the stomach.
Another ring of muscle near the GE junction, the lower esophageal sphincter, allows food from the esophagus into the stomach. When you’re not eating or drinking, it stays closed to keep acid and digestive juices from the stomach out of the esophagus.
The esophagus wall
The esophagus wall consists of four layers: the mucosa, submucosa, muscularis propria and adventitia.
Mucosa. This layer lines the inside of the esophagus and has 3 parts:
- The innermost lining is called the epithelium and is usually made up of squamous cells. Most esophageal cancers start here.
- The thin layer of connective tissue right under the epithelium is called the lamina propria.
- The thin layer of muscle under the lamina propria is called the muscularis mucosa.
Submucosa. Just below the mucosa is a layer of connective tissue called the submucosa that contains blood vessels and nerves.
Muscularis propria. Under the submucosa is a thick layer of muscle called the muscularis propria that helps push food down the esophagus from the throat to the stomach.
Adventitia. Made up of connective tissue, the adventitia is the outermost layer of the esophagus.
Type of esophageal cancer
There are two main types of esophageal cancer, depending on the type of cell it starts in.
Squamous cell carcinoma
Squamous cell carcinoma gets its name because the mucosa, the inner layer of the esophagus, is normally lined with squamous cells. Although it can occur anywhere along the esophagus, squamous cell carcinoma is most often found in the neck region (cervical esophagus) and in the upper two-thirds of the chest cavity (upper and middle thoracic esophagus). Once the most common type of esophageal cancer in the United States, squamous cell carcinoma now comprises less than 30% of esophageal cancers in this country.
Adenocarcinomas are cancers that start in gland cells (the cells that make mucus) and are often found in the lower third of the esophagus (lower thoracic esophagus).
Gastroesophageal (GE) junction tumors
Adenocarcinomas that start at the GE junction, the area where the esophagus joins the stomach, typically behave like cancers in the esophagus and tend to be treated like them.
Causes of esophageal cancer
The causes of most esophageal cancers is not yet known, but there are certain risk factors that can increase the likelihood of getting esophageal cancer.
Inherited gene mutations
When a DNA mutation is passed on through heredity and is found in all of a person’s cells, it’s called an inherited mutation. Inherited gene mutations cause a very small number of esophageal cancers.
Acquired gene mutations
Most cases of esophageal cancer are caused by DNA mutations that aren’t inherited. These are called acquired gene mutations, meaning they’re acquired during a person’s life. While it’s believed that certain risk factors like tobacco and alcohol use do contribute to these acquired mutations, the exact causes are still unknown.