Risk factors for small intestine 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 small intestine cancer develops in people who don’t have any of the risk factors described below.
The risk of developing small intestine cancer increases with age. Most people are diagnosed when they are about 60 years of age. Slightly more men than women develop small intestine adenocarcinoma.
Some people can have a higher than average risk for small intestine cancer. Talk to your doctor about your risk. If you are at higher than average risk, you may need a personal plan for testing.
The following are risk factors for small intestine adenocarcinoma. All 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
There is convincing evidence that the following factors increase your risk for small intestine adenocarcinoma.
The most important risk factor for small intestine adenocarcinoma is having one or more of the following hereditary disorders. These disorders are passed from parent to child through information contained in genes.
Familial adenomatous polyposis (FAP) is usually caused by a mutation of the adenomatous polyposis coli (APC) gene. It causes hundreds to thousands of adenomatous polyps to develop on the inner lining (called the mucosa) of the small intestine, colon and rectum. These polyps have the potential to develop into cancer. Each polyp is no more likely to develop into cancer than polyps in people who don’t have FAP. However, the large number of polyps means that there is a greater risk that cancer could develop. Most small intestine tumours linked to FAP develop in the duodenum (the first part of the small intestine).
Lynch syndrome (also called hereditary non-polyposis colorectal cancer, or HNPCC) is caused by mutations in some of the genes that repair damage to DNA. It causes polyps to grow in the lining of the colon (part of the large intestine) and rectum, but not as many polyps as in FAP. Lynch syndrome puts people at high risk for developing colon and other cancers, including small intestine adenocarcinoma. Small intestine adenocarcinoma often occurs at a younger age in people with Lynch syndrome.
Peutz-Jeghers syndrome is caused by a mutation of the STK11 (also called LKB1) gene. The STK11 gene is normally involved in making a tumour suppressor enzyme. This enzyme helps control cell growth and keeps cells from growing and dividing too fast. Mutations in the STK11 gene prevent this enzyme from working properly so that cells divide too often. People with Peutz-Jeghers syndrome often have hamartomas (a special kind of polyp) in their small and large intestine. These polyps increase the risk of developing colorectal and small intestine cancers.
Cystic fibrosis affects glands that make mucus and sweat, which can in turn affect how well the lungs and digestive tract function. People with cystic fibrosis have a small risk of developing small intestine adenocarcinoma, and some evidence suggests that this risk may be slightly greater after they receive an organ transplant.
Crohn’s disease is an inflammation of the gastrointestinal (GI) tract. It commonly affects the small intestine, especially the last part (called the ileum). Generally, small intestine adenocarcinoma occurs at a younger age in people with Crohn’s disease. But the risk for small intestine adenocarcinoma does not generally increase until a person has had Crohn’s disease for more than 10 years.
Celiac disease (also called sprue) damages the small intestine so that it doesn’t absorb nutrients from food as well as it should. People with celiac disease are sensitive to gluten (a protein found in grains such as wheat, rye and barley). Most people with celiac disease do not develop small intestine adenocarcinoma.
A history of colorectal and other cancers
People who had colorectal cancer have a higher risk of developing small intestine adenocarcinoma. Having other cancers, such as ovarian, stomach and pancreatic cancer, also increases the risk for small intestine adenocarcinoma, but the overall risk is still low.
Unknown risk factors
It isn’t known whether or not the following factors are linked with small intestine adenocarcinoma. It may be that researchers can’t show a definite link or that studies have had different results. More research is needed to see if the following are risk factors for small intestine cancer:
- dietary factors, such as eating red and processed meats or having a high-fat diet
- being overweight or obese
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
The basic biological unit of heredity passed from parents to a child. Genes are pieces of DNA and determine a particular characteristic of an individual.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
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