Cancer InDepth: Esophageal Cancer
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Esophageal cancer is a malignant growth of tissues that line the inner surface of the esophagus.
The esophagus is the tube that connects your throat with your stomach. It runs the length of your chest, between your lungs, behind your heart, and in close proximity to your back bone. The esophagus is a complex, four-layered muscular organ that propels food into your stomach with a series of rhythmic contractions that has three phases. The layers of the esophagus include the mucosa, submucosa, muscularis propria, and adventitia. The depth of cancer invasion is important in regards to determining the stage, prognosis, and appropriate treatment.
Esophageal Cancer
There are two main types of esophageal cancer:
Squamous cell carcinoma —This type of cancer begins in the squamous cells, which are the cells that form the top layer of the lining of the esophagus. Squamous cell carcinoma can occur anywhere in the esophagus. The incidence has been decreasing, accounting for less than 40% of all esophageal cancers in the United States.
Adenocarcinoma —This type of cancer arises from Barrett’s esophagus. Barrett’s esophagus occurs when the squamous cells in the lower esophagus are exposed to acid from the stomach due to acid reflux . The acid causes the cells to change from squamous cells, which are flat, to cells shaped like columns. These column-shaped cells are the hallmark of Barrett’s esophagus and can eventually become an adenocarcinoma.
The incidence of adenocarcinoma, particularly in the United States, has been rising for many years. Around the world, squamous cell carcinoma is the most common type, but in the United States, adenocarcinoma is now the most common, accounting for over 60% of esophageal carcinomas.
Who Is Affected
In the United States there are roughly 12,000 new cases and 12,000 deaths each year. The distribution of this disease is highly unusual, with much higher rates in what appears to be a random pattern: Finland, Iceland, Curaçao, southeast Africa, northeast France, and parts of Asia, extending from west of the Caspian Sea through Iran, the Stans (eg, Kazakhstan and Uzbekistan), and Siberia to Mongolia.
Esophageal cancer is more common in blacks, males, people over 50 years of age, and those of lower socioeconomic status.
Causes and Complications
There are many risk factors for esophageal cancer that appear to be causative. Many are ingested agents that do damage directly to the esophagus, like excess alcohol, nitrates, toxins in pickled vegetables, and very hot beverages. Other irritants that increase the risk of esophageal cancer are radiation, tobacco, smoked opiates, and chronic reflux esophagitis (“heartburn” or gastroesophageal reflux disease).
Ionizing radiation, as experienced by survivors of the “Atomic Bomb,” has been associated with a higher rate of esophageal cancer. Obesity is also associated with a higher risk. Additionally, the condition may run in families. Plummer-Vinson syndrome (a rare disorder characterized by anemia due to a low iron level and low levels of certain nutrients) has been associated with a higher risk for esophageal cancer in women residing in Sweden. Celiac disease , a disorder characterized by malabsorption, has also been linked to this form of cancer.
Esophageal cancer restricts and ultimately prevents swallowing, leading to weight loss, malnutrition, and starvation. Food and liquids not swallowed can be diverted into the lungs, causing choking, aspiration, and pneumonia . Inability to swallow liquids can lead to death by dehydration. Occasionally the cancer erodes into the breathing tubes creating a tracheo-esophageal fistula, through which food passes directly into the lungs.
Metastases from esophageal cancer can lodge anywhere in the body, most frequently ending up in the liver, lungs, brain, and bones. About 90% of patients with this disease die within five years of diagnosis.
References:
Esophageal cancer. National Cancer Institute website. Available at: http://www.nci.nih.gov/cancerinfo/wyntk/esophagus . Accessed December 2, 2002.
Harrison's Principles of Internal Medicine. 14th ed. McGraw-Hill; 1998.
Neoplasms of the esophagus. American Cancer Society website. Available at http://www.cancer.org/docroot/home/index.asp . Accessed November 30, 2002.
Last reviewed November 2008 by Mohei Abouzied, MD
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