Scientists have found several risk factors that make a person more likely to get stomach cancer. Some of these can be controlled, but others cannot. The following factors may raise a person’s risk of developing stomach cancer:
• A Family History of Stomach Cancer
Family history is being looked at as a risk factor for stomach cancer. Brothers, sisters, and children, of people with stomach cancer have an increased risk of getting it themselves. We're not sure whether this is genetic, or because they share other risk factors, such as Helicobacter pylori infection.
• Age
Stomach cancer occurs most commonly in people older than 55. Most people diagnosed with stomach cancer are in their 60s and 70s.
• Anti Inflammatory Drugs
An overview of published studies showed that people who regularly take non steroidal anti inflammatory drugs appear to have a slightly lower risk of stomach cancer. These drugs are called NSAIDs. Examples are aspirin, ibuprofen or Nurofen. Researchers in 2010 reviewed the trials looking at whether daily aspirin can protect against health conditions. They found that taking daily aspirin may reduce the risk of dying from stomach cancer. This needs more research though, and regular use of NSAIDs can increase the risk of developing stomach or duodenal ulcers.
• Being Overweight or Obesity
Excess body weight increases a man’s risk of developing stomach cancer. It is not clear whether obesity increases a woman’s risk of stomach cancer.
• Certain Occupations
Workers in the coal, metal, and rubber industries seem to have a higher risk of getting stomach cancer.
• Common Variable Immune Deficiency (CVID)
People with CVID have an increased risk of stomach cancer. The immune system of someone with CVID can’t make enough antibodies in response to germs. People with CVID have frequent infections as well as other problems, including atrophic gastritis and pernicious anemia. They are also more likely to get gastric lymphoma and stomach cancer.
• Diet
The incidence of stomach cancer in the UK has fallen a great deal since the 1970s. This is probably partly due to better diet. Incidence varies from country to country around the world. This may be explained to some extent by differences in diet. A diet high in very salty foods increases the risk of stomach cancer. Stomach cancer levels are very high in Japan where very salty pickled foods are popular. But these foods are not typically eaten in the UK and stomach cancer rates here are lower than in Japan.
A diet high in certain preserved foods may also increase your risk. Several studies and a large ongoing research study called EPIC have found a small increase in the risk of stomach cancer in people who eat a lot of preserved meat. Preserved meat includes bacon, sausages and ham. These meats contain chemicals called nitrosamines, which have been linked to stomach cancer. A Canadian study found that the increased risk was greatest in people infected with Helicobacter pylori bacteria. Eating a lot of pickled foods may also increase the risk.
A recent study showed that vegetarians may have a lower risk of stomach cancer than meat eaters. And the EPIC study showed an increased risk of stomach cancer for people who eat a lot of red meat. But we need more studies to confirm this.
A diet high in fresh fruit and vegetables seems to reduce the risk of stomach cancer. This may be because these foods contain high levels of antioxidant vitamins. Vitamin C in particular, together with other substances in these fresh foods, may help to prevent damage to the stomach lining that can lead to cancer. Vitamin A has been shown to protect against stomach cancer. One study has also suggested that vitamin B6 may have a protective effect. Research studies have shown that antioxidant vitamins may have the greatest protective effect in people who are under nourished. Antioxident vitamins help in well nourished people too, but their effects are likely to be less. This may explain why some recent studies in America and Europe found no association between fruit and vegetable intake and stomach cancer risk.
• Epstein-Barr Virus (EBV) Infection
Epstein-Barr virus causes infectious mononucleosis (also called mono). Almost all adults have been infected with this virus at some time in their lives, usually as children or teens. EBV has been linked to some forms of lymphoma. It is also found in the cancer cells of about 5% to 10% of people with stomach cancer. These people tend to have a slower growing, less aggressive cancer with a lower tendency to spread. EBV has been found in some stomach cancer cells, but it isn’t yet clear if this virus actually causes stomach cancer.
• Ethnicity/Race
Black people are more likely than white people to develop stomach cancer.
• Gender
Men have twice the risk of developing stomach cancer, compared with women.
• Geography
Worldwide, stomach cancer is more common in Japan, China, Southern and Eastern Europe, and South and Central America. This disease is less common in Northern and Western Africa, South Central Asia, and North America.
• Helicobacter Pylori Infection
Helicobacter pylori is a bacterial infection that has been investigated a lot in the past few years. Infection with this type of bacteria increases the risk of stomach cancer in the lower part of the stomach by around 6 times. Infection with a particular type of HP called cagA positive helicobacter pylori may increase the risk even more. Stomach Cancer Risk Factors.
Millions of people are infected with these bacteria and most of those do not get stomach cancer so other factors must also be at work. Diet and smoking may interact with HP to cause stomach cancer. The bacteria can cause an inflammatory condition called severe chronic atrophic gastritis (SCAG) and this can lead to stomach cancer. People with SCAG have an increased risk of stomach cancer in both the upper and lower parts of the stomach.
Helicobacter infection can be shown on a blood test or a breath test. It can usually be cured fairly easily with a course of antibiotic treatment. But we're not really sure yet how much benefit we get from getting rid of it. HP may protect against a particular type of cancer of the food pipe (oesophagus) called adenocarcinoma of the oesophagus. A meta analysis of studies looking at HP treatment showed that it lowered the risk of stomach cancer a little bit but it may be most effective in people with peptic ulcer or pre cancerous changes. Even if you do have it treated, there is a chance that you will get re infected because it is so common. So your doctor may not treat HP unless you have stomach pains (a symptom of peptic ulcer).
• Hormone Replacement Therapy (HRT)
Women who take hormone replacement therapy (HRT) have a reduced risk of stomach cancer. But HRT increases the risk of some other types of cancer, including breast cancer.
• Inherited Cancer Syndromes
Some inherited conditions may raise a person’s risk of stomach cancer.
- BRCA1 and BRCA2
People who carry mutations of the inherited breast cancer genes BRCA1 or BRCA2 may also have a higher rate of stomach cancer. - Familial adenomatous polyposis (FAP)
In FAP syndrome, people get many polyps in the colon, and sometimes in the stomach and intestines as well. People with this syndrome are at greatly increased risk of getting colorectal cancer and have a slightly increased risk of getting stomach cancer. It is caused by mutations in the APC gene. - Hereditary diffuse gastric cancer
This inherited syndrome greatly increases the risk of developing stomach cancer. This condition is rare, but the lifetime stomach cancer risk among affected people is about 70% to 80%. Women with this syndrome also have an increased risk of getting a certain type of breast cancer. This condition is caused by mutations (defects) in the CDH1 gene. - Hereditary non-polyposis colorectal cancer (HNPCC)
HNPCC, also known as Lynch syndrome, is an inherited genetic disorder that increases the risk of colorectal cancer. People with this syndrome also have an increased risk of getting stomach cancer (as well as some other cancers). In most cases, this disorder is caused by a defect in either the MLH1 or MSH2 gene, but other genes can cause HNPCC, including MLH3, MSH6, TGFBR2, PMS1, and PMS2. - Li-Fraumeni syndrome
People with this syndrome have an increased risk of several types of cancer, including developing stomach cancer at a relatively young age. Li-Fraumeni syndrome is caused by a mutation in the TP53 gene. - Peutz-Jeghers syndrome (PJS)
People with this condition develop polyps in the stomach and intestines, as well as in other areas including the nose, the airways of the lungs, and the bladder. The polyps in the stomach and intestines are a special type called hamartomas. They can cause problems like bleeding or blockage of the intestines. PJS can also cause dark freckle-like spots on the lips, inner cheeks and other areas. People with PJS have an increased risk of cancers of the breast, colon, pancreas, stomach, and several other organs. This syndrome is caused by mutations in the gene STK1.
• Menetrier Disease (Hypertrophic Gastropathy)
In this condition, excess growth of the stomach lining causes large folds in the lining and leads to low levels of stomach acid. Because this disease is very rare, it is not known exactly how much this increases the risk of stomach cancer.
• Pernicious Anemia
Certain cells in the stomach lining normally make a substance called intrinsic factor (IF) that we need to absorb vitamin B12 from foods. People without enough IF may end up with a vitamin B12 deficiency, which affects the body’s ability to make new red blood cells and can cause other problems as well. This condition is called pernicious anemia. Along with anemia (too few red blood cells), people with this disease have an increased risk of stomach cancer.
• Previous Stomach Surgery
Stomach cancers are more likely to develop in people who have had part of their stomach removed to treat non-cancerous diseases such as ulcers. This might be because the stomach makes less acid, which allows more nitrite-producing bacteria to be present. Reflux (backup) of bile from the small intestine into the stomach after surgery might also add to the increased risk. These cancers typically develop many years after the surgery.
• Radiation Exposure
Atomic bomb survivors in the 2nd World War were more likely to get stomach cancer because of the radiation they were exposed to. And we've known for many years that people who have had radiotherapy to the spine for a condition called ankylosing spondylitis have an increased risk.
Stomach cancer has also been linked to medical X-ray exposure in the past. These days, the amount of radiation used in a regular X-ray is much lower than it used to be. But some other medical tests, such as CT scans, use a significant amount of radiation. This is not harmful to you if you have scans only when you need them. But it explains why doctors are reluctant to use scans for routine screening.
• Some Types of Stomach Polyps
Polyps are non-cancerous growths on the lining of the stomach. Most types of polyps (such as hyperplastic polyps or inflammatory polyps) do not seem to increase a person’s risk of stomach cancer, but adenomatous polyps – also called adenomas – can sometimes develop into cancer.
• Stomach Lymphoma
People who have had a certain type of lymphoma of the stomach known as mucosa-associated lymphoid tissue (MALT) lymphoma have an increased risk of getting adenocarcinoma of the stomach. This is probably because MALT lymphoma of the stomach is caused by infection with H pylori bacteria.
• Tobacco and Alcohol Use
Cigarette smoke contains many cancer causing chemicals. When you breathe in cigarette smoke, you will always swallow some of it without meaning to. In that way, smoking can increase the risk of stomach cancer. About 1 in 5 stomach cancers (20%) in the UK is thought to be caused by smoking.
People who smoke have around twice the risk of stomach cancer compared to non smokers. The risk falls if you stop smoking. If smokers have HP infection, they may have more than 10 times the risk of non smokers without HP infection. A Swedish study showed that non smokers who use a type of chewing tobacco called snus increase their risk of stomach cancer by up to a half. From recent research it seems unlikely that drinking alcohol increases the risk of stomach cancer.
• Type A Blood
Blood type groups refer to certain substances that are normally present on the surface of red blood cells and some other types of cells. These groups are important in matching blood for transfusions. For unknown reasons, people with type A blood have a higher risk of getting stomach cancer. Stomach Cancer Risk Factors.