The esophagus is a long hollow tube that carries swallowed food from the throat to the stomach for digestion. Cancer begins when the cells that form the lining of the esophagus begin to grow abnormally. Esophageal cancer can occur anywhere along the length of the esophagus, from the throat to the stomach and usually starts in the inner layer of the esophagus wall and grows outward.
Two Main Types of Esophageal Cancer
Squamous cell carcinoma starts in the squamous cells found lining the inner layer of the esophagus. It is most commonly found in the neck area and in the upper two thirds of the chest cavity. Squamous cell carcinoma can be caused by environmental factors including exposure to asbestos, cigarette smoke and drinking alcohol.
Adenocarcinoma starts in the cells that make mucus, called gland cells. This type of esophageal cancer is commonly found in the lower third of the esophagus. Adenocarcinoma is higher in people who suffer from gastric reflux. Over time, stomach acid can damage the inner lining of the esophagus and cause cancerous changes to the cells.
Other cancers, such as melanomas, lymphomas, and sarcomas, can also start in the esophagus but are rare.
Symptoms of Esophageal Cancer
Trouble swallowing or dysphagia is the most common symptom of esophageal cancer. Food may also feel like it is stuck in the throat or chest. Choking is not uncommon and the risk of choking increases as the disease progresses. As the cancer grows it causes the opening inside the esophagus to narrow and get smaller making it difficult and even painful to swallow food.
Chest pain or burning in the chest with or without a feeling of pressure has been reported as a symptom.
Weight loss can be connected to problems with swallowing that cause a decrease in the amount of food that is eaten, leading to unintended weight loss. Cancer may also decrease a person’s appetite and increase metabolism leading to weight loss.
Hoarseness that becomes chronic and a rough voice can be a sign of esophageal cancer.
Chronic cough is usually caused by an airway irritation due to saliva or food going into the airway because the esophagus is blocked by a tumor.
Vomiting blood is usually not the first sign of cancer but may develop later if the cancer growth is rapid. Vomiting blood may also occur as parts of a tumor become necrotic and die. As blood from the esophagus passes through the digestive tract it may turn the stool black.
Bone pain occurs if esophageal cancer has spread to the bone.
Bleeding into the esophagus leads to blood being passed through the digestive tract, which may turn the stool black. Blood loss can lead to anemia and fatigue.
Risk Factors
Tobacco: The use of cigarettes, pipes, chewing tobacco, cigars and snuff increase the risk of esophageal cancer.
Environmental exposure to a known carcinogen: Inhalation or ingestion of a known carcinogen, such as asbestos.
Alcohol: Heavy drinking increases the risk, particularly of squamous cell carcinoma. The risk is further increased if drinking is combined with smoking.
Acid Reflux: Stomach acid damages the lining of the esophagus causing cellular changes.
Diet: A diet lacking in fruits and vegetables increases cancer risk.
Asbestos and Esophageal Cancer
Asbestos fibers are strong, resistant to heat and do not conduct electricity. These properties make asbestos a common material for insulation, automobile parts, roofing shingles, floor tiles and a multitude of other products. As evidence of the negative effect asbestos had on human health became apparent, measures were taken to limit exposure to asbestos.
Asbestos is made of silicon and oxygen but may also contain other particles. There are two types of asbestos, chrysotile, and amphibole.
Chrysotile, or white asbestos, is commonly used for industrial purposes, and is characterized by microscopic fibers that wrap around themselves in a spiral. Chrysotile asbestos is also called curly or serpentine.
Amphibole asbestos has fibers that are straight like a needle and are divided into several types. It is believed that the smaller, straighter fibers of amphibole asbestos are more dangerous because they can penetrate deeper into the body.
A carcinogen is defined as any substance that causes cancer or helps cancer to grow. Multiple expert agencies have studied asbestos and evaluated its properties. The American Cancer Society looks to these organizations for information on substances that are deemed a carcinogen and dangerous to humans.
The International Agency for Research on Cancer (IARC) classifies asbestos as carcinogenic to humans.
The National Toxicology Program (NTP) is a group of several US government agencies, including the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA). The NTP has also deemed asbestos as a human carcinogen.
The Integrated Risk Information System (IRIS) is an electronic database with information on substances in the environment that have human health consequences. IRIS is maintained by the US Environmental Protection Agency (EPA) and has asbestos listed as a known human carcinogen.
Asbestos Exposure
Exposure to asbestos can occur in different ways. A common exposure route is through inhaling airborne asbestos fibers. When asbestos is mined, or insulation fabricated and installed, the process creates a dust of tiny asbestos particles that can easily be breathed in. Asbestos fibers can become trapped in the lining of the esophagus causing damage to the cells, leading to cancer.
Asbestos fibers can be swallowed when food or water is contaminated. Coughing fibers from the lungs and then swallowing saliva can introduce asbestos into the digestive system.
Facts About Esophageal Cancer
Esophageal Cancer is the eleventh leading cause of cancer in the United States and it is projected that 18,440 new cases will be diagnosed in 2020.
Symptoms of esophageal cancer aren’t often noticed until the cancer is advanced. Prompt treatment when symptoms appear is critical to successful management of the disease. Discussions with a doctor about any environmental exposure, such as asbestos exposure, increases the odds of a timely diagnosis.
