Risks for stomach cancer

Certain behaviours, substances or conditions can affect your risk, or chance, of developing cancer. Some things increase your risk and some things decrease it. Most cancers are the result of many risks. But sometimes cancer develops in people who don't have any risks.

Helicobacter pylori infection is the main risk for stomach cancer.

More men than women develop stomach cancer. The risk of developing stomach cancer increases with age and is greatest after 50 years of age. Some studies show that low socio-economic status is linked with a higher rate of stomach cancer.

Stomach cancer is most common in Japan, China, South America and Eastern Europe. It is not as common in North America. In Canada, the number of new cases of stomach cancer diagnosed each year has been going down since the 1980s.

Precancerous conditions of the stomach include gastric epithelial dysplasia and gastric adenoma. They are not cancer, but they can sometimes become stomach cancer if they are not treated. Some of the things that increase the risk for stomach cancer may also cause these precancerous conditions. Find out more about precancerous conditions of the stomach.

Some people with certain genetic conditions have a higher than average risk for stomach cancer. Talk to your doctor about your risk. If you have a genetic condition that increases the risk of stomach cancer, you may need to visit your doctor more often to check for stomach cancer. Your doctor will recommend what tests you should have and how often you should have them.

The following can increase or decrease your risk for stomach cancer. There are things you can do to lower your risk and help protect you from developing cancer.

Certain infections

Smoking tobacco

Family history of stomach cancer

Genetic conditions

Certain stomach conditions

Previous stomach surgery

Contact with ionizing radiation

Working in the rubber industry

Type A blood

Alcohol

Excess weight

Salt and salty foods

Infections with the following viruses and bacteria increase the risk of developing stomach cancer.

Helicobacter pylori (H. pylori) is a type of bacteria that causes stomach ulcers and inflammation of the stomach lining (called gastritis). While H. pylori can increase the risk, not all people infected with H. pylori will develop stomach cancer. H. pylori may act with other factors to increase the risk of developing stomach cancer. The age when you are infected may also affect your risk of developing stomach cancer.

Learn more about Helicobacter pylori (H. pylori) and how to reduce your risk of H. pylori infection.

Epstein-Barr virus (EBV) is a type of herpes virus that causes infectious mononucleosis (also called mono, or the "kissing disease"). Infection with EBV may increase the risk of developing non-Hodgkin lymphoma of the stomach, which is a rare type of stomach cancer. It may also increase the risk of developing adenocarcinoma, the most common type of stomach cancer.

Learn more about Epstein-Barr virus (EBV).

Smoking tobacco increases your risk for stomach cancer.

All forms of tobacco, including cigarettes, cigars and pipes, increase your risk.

The more you smoke and the longer you smoke, the greater your risk. The risk of developing stomach cancer decreases with time after you quit smoking.

Learn more about how to live smoke-free.

If you have a first-degree relative who has had stomach cancer, you have a higher risk of developing stomach cancer. The higher risk may be due to inherited conditions. It may also be because family members have the same risk factors such as diet, smoking and H. pylori infection.

Learn more about cancer risk in families.

A genetic condition is a disease caused by a change (mutation) in one or more genes. Having certain genetic conditions increases the risk of developing stomach cancer.

Hereditary diffuse gastric cancer (HDGC) increases the risk of developing diffuse adenocarcinoma (gastric cancer). With this type of cancer, the cancer cells are spread throughout the stomach lining and don't form a tumour in one area. Stomach cancer linked with HDGC usually develops before the person is 40 years of age. Doctors may suspect HDGC when stomach cancer develops in several members of a family.

Familial adenomatous polyposis (FAP) is an inherited condition that causes hundreds to thousands of polyps to develop, mainly on the lining of the colon and rectum.

People with FAP have a higher risk of developing colorectal cancer and small intestine cancer. FAP also increases the risk of stomach, adrenal gland and thyroid cancers.

Lynch syndrome is an inherited condition that causes a large number of polyps to develop in the lining of the colon and rectum, but not as many polyps as are found in familial adenomatous polyposis (FAP). Lynch syndrome is also called hereditary non-polyposis colorectal cancer (HNPCC).

There are 2 types of Lynch syndrome. Type A increases the risk for colorectal cancer, while type B increases the risk of several cancers, including colorectal cancer and other digestive system cancers, and ovarian and uterine cancers in women.

Peutz-Jeghers syndrome is an inherited condition that causes dark spots on the mouth and fingers and polyps in the large and small intestines.

Peutz-Jeghers syndrome increases the risk of developing colorectal, small intestine, stomach, pancreatic, breast and other types of cancer.

Juvenile polyposis syndrome causes polyps to grow in the gastrointestinal (GI) tract, including the stomach, before age 20.

Li-Fraumeni syndrome is an inherited condition that is associated with an increased risk of developing certain types of cancers, including breast cancer, brain tumours, acute leukemia, soft tissue and bone sarcomas and adrenal cortical carcinomas.

People with Li-Fraumeni syndrome tend to develop several different types of cancer before the age of 45.

Breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) normally help control the growth of cancer cells. Changes in these genes (which can be inherited from either parent) increase the risk for breast and ovarian cancers.

Learn more about genes and cancer.

The following non-cancerous stomach conditions increase the risk of developing stomach cancer.

Chronic atrophic gastritis is when the lining of the stomach becomes inflamed. It is usually caused by an infection with H. pylori. It can also develop if the immune system attacks healthy tissues of the stomach lining by mistake (called autoimmune atrophic gastritis).

Intestinal metaplasia is when cells in the stomach are replaced by cells that normally line the intestines. It may be caused by H. pylori infection, inherited conditions, diet or other factors.

Ménétrier disease is a rare disease that causes cells in the lining of the stomach to grow too much and form large folds in the lining.

Pernicious anemia is a type of anemia (a lower than normal number of red blood cells) that develops when the GI tract can't absorb vitamin B12. The body needs vitamin B12 to make red blood cells. People with pernicious anemia may develop polyps in the stomach.

Surgery to remove part of the stomach is called partial gastrectomy. This surgery may be used to treat stomach ulcers. People who have had stomach surgery have a higher risk of developing stomach cancer. This may be because bile from the small intestine moves into the remaining stomach and causes inflammation. It is not clear if this happens because of H. pylori infection, because the stomach makes less stomach acid or because of other reasons.

Surgery to treat ulcers in the first part of the small intestine (called the duodenum) doesn't seem to increase the risk for stomach cancer.

People who came in contact with ionizing radiation from atomic bomb explosions in Japan during the Second World War have a greater risk of developing stomach cancer, especially if they were children when they came in contact with the radiation. Studies have shown that people exposed to radiation from nuclear accidents or fallout are also at higher risk of developing stomach cancer.

Some studies suggest that people treated with some forms of radiation therapy have a higher risk of developing stomach cancer. This includes people who were treated with a radioisotope for thyroid cancer and people given radioisotope for thyroid cancer and people given external beam radiation therapy for Hodgkin disease. The risk of developing stomach cancer after radiation therapy depends on many factors. Only a very small number of people develop cancer because of radiation therapy treatments. The benefit of treating a cancer often greatly outweighs the risk of developing stomach cancer later on.

People who work in the rubber manufacturing and processing industry have a higher risk of developing stomach cancer. This is because they come into contact with cancer-causing chemicals commonly used in the rubber industry.

Learn more about how to be safe at work.

People with type A blood have a higher risk of developing stomach cancer, but the reason for this is not known.

Drinking alcohol increases your risk for developing stomach cancer. The less alcohol you drink, the lower your cancer risk.

Learn more about how to limit alcohol.

Overweight increases the risk for stomach cancer. Learn more about how to have a healthy body weight.

There is evidence that eating salt and salty foods, including salt-preserved and salted foods, increases the risk for stomach cancer. There is also a link between salt intake and developing intestinal metaplasia.

Researchers are not sure if salt increases your risk for stomach cancer on its own, or if it increases the risk when it is combined with other risk factors like H. pylori.

Studies also link the lack of food refrigeration to a higher risk for stomach cancer. This is probably because people who don't have access to refrigeration often use salt to preserve their food.

Limit the amount of salt and salty foods you eat. Limit the amount of salt you use in cooking and add less salt to your food at the table. Learn more about how to eat less salt.

The following have been linked with stomach cancer, but there is not enough evidence to know for sure that they are risks. More research is needed.

• not eating enough vegetables and fruit
• smoked, cured and processed meats
• grilled and barbecued meats
• gastroesophageal reflux disease (GERD)
• contact with lead at work
• asbestos

Significant evidence shows no link between stomach cancer and proton pump inhibitors (drugs that lower stomach acid) or wood dust.

To make the decisions that are right for you, ask your healthcare team questions about risks. Learn how cancer can be prevented and what you can do to reduce your risk.