Types of Esophageal Cancer
Esophageal cancer is treated depending on the cell type and its location in the esophagus. The esophagus is a tube with multiple layers whose function is to transport food from the mouth to the stomach. Esophageal cancer usually arises from the innermost layer of the esophagus and can be present anywhere along its length. The two most common types of esophageal cancer are adenocarcinoma and squamous cell carcinoma. In the U.S. the incidence of esophageal adenocarcinoma is increasing compared to esophageal squamous cell cancer, which is more prevalent worldwide. The location of the cancer in the esophagus also guides associated symptoms and treatment.
This is the most common type of esophageal cancer in the U.S. It occurs mostly in the distal portion of the esophagus and esophagogastric junction, but can cross into the proximal stomach also. Recent advances in targeting specific changes or mutations in the tumor DNA of this cancer can help guide the treatment and prognosis.
Risk factors for Adenocarcinoma are:
Gastro-Esophageal Reflux Disease (GERD) - This is defined as symptomatic acid reflux that manifests as heartburn or regurgitation. It affects 20% of all adults in the U.S., causes cell damage in the esophagus as a result of acid exposure.
Intestinal metaplasia (Barrett’s Esophagus) - As result of chronic acid reflux, the cells in the lining of the esophagus transform to become more resistant to acid, which can lead to dysplasia. The risk of developing esophageal cancer is ~ 2% per year, without treatment.
Obesity - This is defined as having a Body Mass Index (BMI) > 30, and represents over 1 in 3 adults in the U.S. Obesity is a risk factor because it correlates highly with the presence of GERD.
Smoking - Smoking 1 pack of cigarettes per day is associated with a 2 X increased risk, yet this risk goes down if smoking stops.
Alcohol - Increased consumption is associated with increased risk of GERD, and risk is worse with smoking and alcohol together.
Achalasia - An idiopathic condition causing the lower esophageal sphincter (LES) to not relax and is treated with dilation or myotomy of LES, can then lead to uncontrolled GERD.
Squamous Cell Cancer
This is now the second most common subtype of esophageal cancer in the U.S., but remains the most common type worldwide. It occurs mostly in the proximal and middle portions of the esophagus. It is associated with high alcohol intake and smoking.
Risk factors for Squamous Cell cancer are:
Alcohol - This is a known carcinogen, and chronic high alcohol consumption is one of the major risk factors for squamous cell cancer. The risk does decrease with stopping consumption, but does not equal that of non-drinker for at least 15 years after abstinence.
Smoking - This is also a known carcinogen, by itself and in conjunction with high alcohol consumption, are the two main risk factors.
Lye Ingestion - This causes chemical injury to the cell lining the esophagus and can manifest with esophageal stricture and squamous cell cancer many years later.
Achalasia - An idiopathic condition causing the lower esophageal sphincter (LES) to not relax and thereby not allowing food to pass into the stomach. This cause dilation of esophagus and food to remain in the esophagus causing injury to the cells lining the esophagus.
Tylosis - This is a rare, inherited disease that causes excess growth of the top layer of skin on the palms of the hands and soles of the feet. People with this condition also develop small growths (papillomas) in the esophagus and have a very high risk of getting squamous cell cancer of the esophagus.
Human Papilloma Virus (HPV) Infection - Certain strains of this virus are associated with increased risk, as they have been found in squamous cell esophageal cancer.
History of Squamous Cell Cancer - If you have had squamous cell cancer in the lung, mouth, or throat in the past, your risk for esophageal squamous cell cancer is higher also.