Understanding the Disease
Esophageal cancer is the sixth leading cause of cancer death in the world, although it remains relatively uncommon in North America. The National Cancer Institute estimates that over 15,000 new esophageal cancers will be diagnosed in the United States in the year 2007. This represents one percent of all cancers and nearly 10 percent of gastrointestinal cancers. Despite its relative rarity, the death rate remains high with an estimated 13,300 deaths attributed to esophageal cancer annually.
In the past two decades, dramatic change has occurred in the types of esophageal cancer that are most prevalent. Adenocarcinoma has replaced squamous cell carcinoma as the most common esophageal cancer in most western countries. The incidence of adenocarcinoma has risen faster than any other form of cancer. While squamous cell carcinoma remains the most common type of esophageal cancer in the world, the incidence of adenocarcinoma in North America has increased nearly 600 percent.
Historically, less than 15-20 percent of patients diagnosed with esophageal cancer were likely to survive five years. However, with recognition of the risk factors causing esophageal cancer, earlier discovery and better treatment plans, the modern 5-year survival rate in 2007 has risen to over 50 percent.
Introduction to Esophogeal Cancer
In the video below, Thoracic Surgeon, Dr. Brian Louie explains esophageal cancer.
The esophagus is the muscular tube that conveys food from the back of the throat to the stomach. It is located in the chest behind the sternum and the trachea, the main breathing tube leading to the lungs. The esophagus joins the stomach at the diaphragm, which is the breathing muscle separating the chest and lungs from the abdomen. The connection of the esophagus to the stomach at the diaphragm is called the gastro-esophageal junction. The gastro-esophageal junction serves as a one-way valve to keep stomach contents from being refluxed or regurgitated back into the esophagus.
Types of Esophageal Cancer
The esophagus can be divided into thirds: proximal or neck; middle or chest; lower or abdominal. Most cancers of the upper two thirds of the esophagus arise from squamous cells and are called squamous cell or epidermoid cancers. Cancers of the lower esophagus are called adenocarcinomas and arise in pre-cancerous cells caused by heartburn or GERD.
There are clear differences in the profiles of patients with squamous cell carcinoma and adenocarcinoma of the esophagus. Esophageal adenocarcinoma is more common in white males and is strongly associated with a history of chronic gastroesophageal reflux disease (GERD). It also tends to occur at a younger age (50-60). In contrast, squamous cell carcinoma is more common in minority populations including Asian Americans and African Americans, and is also more strongly linked to tobacco and alcohol use.
- Smoking and alcohol play a major role in the development of many cancers and are the key risk factors in the development of squamous carcinoma of the esophagus.
- Chronic gastroesophageal reflux disease or GERD is thought to be the cause of adenocarcinoma of the esophagus. In a recent study, patients who had GERD more than three times per week for over 20 years were 20 times more likely to develop this type of esophageal cancer.
Exactly how chronic GERD leads to the development of an esophageal cancer is still being researched, but what we know at the present time is that once food has emptied into the stomach, it is mixed with enzymes, acids from the stomach and bile from the gall bladder.
If stomach contents reflux or regurgitate back into the esophagus, the surface lining can be damaged by one or all of these contents. The normal squamous lining becomes damaged and over time is replaced by specialized cells to protect the esophagus. These specialized cells are referred to as Barrett's esophagus and are more prone to become cancerous.
The precise risk of developing adenocarcinoma in patients with Barrett's esophagus is unknown. However, estimates indicate the lifetime risk falls somewhere between 30 to 125 times that of the general population.
(For related information see Barrett's Esophagus, GERD and Hiatal Hernia)
- Initially, they may feel subtle sensations of food sticking the esophagus. Over time, the sensation changes and feels like food is sticking in the esophagus, a condition known as dysphagia. Weight loss and a decreased appetite often follow. Dysphagia is often the symptom that prompts a patient to seek medical attention.
- The cancer may also be discovered during evaluation for symptoms of chronic heartburn, regurgitation or gastrointestinal bleeding. Patients with longstanding GERD or known Barrett's esophagus may be periodically evaluated by their physician and the cancer found during one of these exams.
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