VOLUNTEERS ARE URGENTLY NEEDED IN APRIL
Risk factors for esophageal cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. But sometimes esophageal cancer develops in people who don’t have any of the risk factors described below.
The most common types of esophageal cancer are adenocarcinoma and squamous cell carcinoma (SCC). Some risk factors are common to both types of esophageal cancer, but other risk factors are linked with only adenocarcinoma or SCC.
Men are more likely to be diagnosed with cancer of the esophagus than women. Most people diagnosed with esophageal cancer are men over the age of 60. The highest rates of esophageal cancer occur in parts of China, Iran, South America, France and Africa.
The following are risk factors for esophageal cancer. Some of the known risk factors are not modifiable. This means that you can’t change them. Until we learn more about these risk factors, there are no specific ways you can reduce your risk.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
|Known risk factors||Possible risk factors*|
*You may wonder about Helicobacter pylori (H. plylori) infection and carbonated beverages. There is significant evidence showing that there is no association between these factors and esophageal cancer.
Known risk factors
There is convincing evidence that the following factors increase your risk for esophageal cancer.
Using any kind of tobacco has been linked to the development of esophageal cancer. Tobacco use combined with drinking alcohol increases the risk of developing esophageal cancer more than either risk factor alone.
The risk of developing both squamous cell carcinoma (SCC) and adenocarcinoma of the esophagus increases the longer and the more you smoke.
Smoking causes both SCC and adenocarcinoma of the esophagus, but smokers are more likely to develop SCC. Smokers have a much higher risk of developing SCC of the esophagus than non-smokers. Heavy smokers are at even greater risk of developing SCC of the esophagus than non-smokers.
Researchers have shown that the risk of developing SCC of the esophagus decreases after you stop smoking. For adenocarcinoma of the esophagus, the risk is lower in former smokers than in current smokers. It is not clear how much a person’s risk decreases after they stop smoking.
Pipes and cigars
People who smoke pipes and cigars have a higher risk of developing SCC of the esophagus.
Researchers have shown that smokeless tobacco increases the risk for both SCC and adenocarcinoma of the esophagus.
Drinking alcohol is a risk factor for SCC of the esophagus. The more alcohol you drink, the greater your risk. It is not known for sure if alcohol is a risk factor for adenocarcinoma of the esophagus.
Drinking alcohol combined with using tobacco increases the risk of esophageal cancer more than either risk factor alone.
Betel quid, or paan, is areca nut with lime wrapped in a betel leaf. Chewing betel quid is common in China, India and some other countries in Asia and among some Asian immigrants to Canada.
Betel quid contains cancer-causing substances that increase the risk of developing SCC of the esophagus. Betel quid and tobacco are often chewed together, but there is a risk of developing SCC of the esophagus whether or not tobacco is also chewed.
Gastroesophageal reflux disease (GERD) is a disorder in which the contents of the stomach (including stomach acid) back up, or reflux, into the esophagus. This causes heartburn and discomfort in the upper abdomen or chest. The stomach acid can damage the tissue at the lower end of the esophagus.
Barrett’s esophagus can develop if reflux occurs over a long period of time. Normal squamous cells in the lining of the esophagus can change and become more like the cells that line the stomach (glandular columnar cells). This process is called metaplasiametaplasiaChanges in mature, specialized cells to a form that is abnormal for that tissue. Cells look normal under a microscope, but are not the type of cell usually found in the tissue.. When metaplastic cells are in the esophagus, it is called Barrett’s esophagus. Barrett’s esophagus is a precancerous condition that increases the risk of developing adenocarcinoma of the esophagus.
Tylosis is a rare inherited disease that increases the risk of developing esophageal cancer. Researchers have identified the tylosis esophageal cancer (TOC) gene. People with this abnormal gene develop scaly patches (hyperkeratosis) on the palms of the hands or soles of the feet. They also have papillomas (growths with finger-like projections) in the esophagus.
Achalasia is an uncommon condition in which the nerves that control the normal rhythmic contractions in the esophagus and the lower esophageal sphincter do not work properly. The part of the esophagus above the sphincter becomes enlarged, and the person has a hard time swallowing food and liquid.
Researchers think that achalasia increases the risk for SCC of the esophagus because food trapped in the esophagus can cause chronic irritation. After symptoms start, it can take many years for cancer to develop.
Plummer-Vinson syndrome is also called Paterson-Kelly syndrome. In this rare syndrome, the mucous membranes of the mouth, pharynx and esophagus waste away. A thin membrane of tissue (known as an esophageal web) can also grow anywhere along the esophagus, which causes problems swallowing. Doctors think Plummer-Vinson syndrome is caused by a lack of vitamins and iron. People with this syndrome often have iron-deficient anemia.
About 10% of people with Plummer-Vinson syndrome will develop SCC of the esophagus. Researchers think that this syndrome increases the risk for SCC of the esophagus because it causes nutritional problems and food trapped in the webs can cause chronic irritation.
The esophagus can be damaged by exposure to chemicals. Drinking a caustic chemical such as lye can lead to strictures (narrowed areas) in the esophagus. SCC of the esophagus can occur in these strictures many years after the chemical injury.
People who had cancer that started in the upper airway, such as oral, pharyngeal (throat) or laryngeal cancer, are at risk for SCC of the esophagus. These cancers have some of the same risk factors as esophageal cancer, such as tobacco and alcohol use.
People who were exposed to ionizing radiation have a higher risk of developing esophageal cancer, mainly SCC of the esophagus.
Women who had radiation to the chest have an increased risk of developing SCC of the esophagus. The risk that this cancer will develop starts 5 years after radiation therapy and continues for another 10 years. Studies have shown that the risk of developing adenocarcinoma of the esophagus after medical radiation is much less.
Ankylosing spondylitis is a type of arthritis that affects the spine. People who were given x-ray therapy to treat this disease have a higher risk of developing SCC of the esophagus.
The benefit of treating breast cancer and other diseases often greatly outweighs the risk of developing esophageal cancer later in life. Find out more about medical radiation.
Atomic bomb survivors
People who were exposed to ionizing radiation during atomic bomb explosions in Japan during the Second World War have a greater risk of developing esophageal cancer.
Body mass index (BMI) is a measure that relates body weight to height. It is calculated by dividing your weight in kilograms by your height in metres squared.
A very low BMI may mean that the person is underweight. It is often linked with malnutrition, which is a risk factor for SCC of the esophagus.
A high BMI means that a person is overweight or obese, which is a risk factor for adenocarcinoma of the esophagus. High BMI is linked with GERD and Barrett’s esophagus, which may explain the relationship between a high BMI and adenocarcinoma of the esophagus.
People with a family history of esophageal cancer have a higher risk of developing this cancer. Family history may be more important for people who smoke or drink large amounts of alcohol. Several studies of people who live in China, where esophageal cancer rates are high, found a genetic link to the development of the disease. Family history does not seem to be as important a risk factor in people who live in Canada or the United States.
People who drink very hot coffee, tea, maté and other beverages (hotter than 65°C) have a higher risk of developing esophageal cancer, particularly squamous cell carcinoma. Hot maté is made by pouring boiling water over leaves of the yerba maté plant and is drunk through a metal straw. Drinking very hot maté is common in South American countries. Drinking very hot tea or coffee is common in China, Japan, Iran and Turkey.
The following factors have been linked with esophageal cancer, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for esophageal cancer.
Exposure to dry cleaning chemicals
Tetrachloroethylene (also known as perchloroethylene, perc or PCE) and trichloroethylene are chemicals used in the dry cleaning industry. Exposure to these chemicals may increase a person’s risk of developing esophageal cancer. Other known risk factors may be involved, such as alcohol and tobacco use.
A diet low in vegetables and fruit
There appears to be an increased risk of developing squamous cell carcinoma of the esophagus when a person’s diet is low in the nutrients found in vegetables and fruit, such as vitamins A, C and E, selenium, carotenoids and fibre.
Eating red meat
Eating red meat (beef, pork, lamb and goat) may increase the risk of developing esophageal cancer. The more red meat a person eats, the greater the risk seems to be. Cooking meat at high temperatures creates chemicals called heterocyclic amines (HCAs), which may increase the risk for SCC of the esophagus. Frying, broiling and barbequing cook meat at high temperatures.
Eating processed meat
Processed meat includes meats preserved by curing, smoking, salting or adding preservatives. Preserved meats contain nitrates, while smoked or cured meats contain nitrites. Under certain conditions in the body, both nitrates and nitrites are changed into cancer-causing nitrosamines. Nitrosamines increase the risk of SCC of the esophagus.
Vitamins A and C have a protective effect against nitrosamines. When the intake of vitamins A and C is low and the intake of nitrates and nitrites is high, the risk of developing cancer of the esophagus is even higher.
Researchers are studying changes, or mutations, to genes that contribute to the development of cancer. Changes to a gene can stop the gene from working properly and cause cancer.
Mutation of TP53, a tumour suppressor gene, is linked with cancer of the esophagus. The BRCA2 gene mutation is also seen in esophageal tumours.
Researchers are also studying mutations of the genes involved in alcohol and tobacco metabolism. Some studies show a link between these genes and the development of esophageal cancer.
Cystic fibrosis is a genetic condition that affects glands that make mucus and sweat. It can affect how well the lungs and gastrointestinal (GI) tract work. A large study followed people with cystic fibrosis for 20 years. The study showed that they may have a higher risk of developing cancer in the area where the esophagus joins the stomach (called the gastroesophageal, or GI, junction).
Unknown risk factors
It isn’t known whether or not the following factors are linked with esophageal cancer. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if the following are risk factors for esophageal cancer:
- celiac disease (a medical condition caused by a sensitivity to gluten)
- pernicious anemia (a medical condition caused by the body’s inability to absorb vitamin B12)
- exposure to certain chemicals, including asbestos, silica dust and cement dust
- working in certain industries, including chimney sweeping, meat-packing and slaughtering, asphalt laying, printing, oil and gas, rubber manufacturing, dyeing, metal working and the automobile industry
- human papilloma virus (HPV) infection
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
Clinical trial discovery improves quality of life
A clinical trial led by the Society’s NCIC Clinical Trials group found that men with prostate cancer who are treated with intermittent courses of hormone therapy live as long as those receiving continuous therapy.