A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for many cancers. But risk factors don't tell us everything. Someone without any risk factors can develop cancer, and having a risk factor, or even several, does not mean that you will get the disease. Because small intestine adenocarcinoma is so uncommon, risk factors for this disease have been hard to study. Some of the known risk factors include:

Sex

Small intestinal adenocarcinoma occurs slightly more often in men than in women.

Age

Small intestinal adenocarcinoma becomes more common as people get older. The average age at diagnosis is about 60.

Smoking and alcohol use

Some, but not all, studies have found an increased risk with either smoking or alcohol use.

Celiac disease

This disease is also known as celiac sprue and gluten-sensitive enteropathy. Gluten is a protein that is found in many types of grain, including wheat, rye, barley, and oats. In someone with celiac disease, eating gluten causes an immune reaction. The body makes antibodies that attack the lining of the intestines. This makes it hard to digest and absorb food, leading to diarrhea and weight loss. People with celiac disease have an increased risk of small intestine cancers, including lymphoma and adenocarcinoma. Staying on a gluten-free diet seems to lower the risk of cancer in someone with this disease.

Colon cancer

Survivors of colon cancer have an increased risk of getting cancer of the small intestine. This may be due to shared risk factors.

Crohns disease

Crohns disease is a condition in which the immune system attacks the gastrointestinal (GI) tract. This disease can affect any part of the GI tract, but it most often affects the lower part of the small intestine. People with this problem have a risk of small bowel adenocarcinoma that is about 28 times higher than normal. These cancers are most often seen in the ileum.

Diet

A recent study has shown that a diet high in fiber may help lower the risk of small intestine cancer.

Inherited causes

People with certain inherited conditions have a higher risk of small intestine adenocarcinoma.

• Familial adenomatous polyposis (FAP): In this condition, many (even hundreds) of polyps develop in the colon and rectum. If the colon isn't removed, one or more of these polyps will become cancerous. Polyps in the stomach and the small intestine are also part of this syndrome, and they can lead to cancers in these areas. In FAP, most small intestine cancers are found in the duodenum. This condition is caused by an abnormal copy (mutation) of the gene APC and is discussed more in our document, Colorectal Cancer.

• Hereditary nonpolyposis colorectal cancer (HNPCC): Another name for HNPCC is Lynch syndrome. In most cases, this disorder is caused by a defect in either the gene MLH1 or the gene MSH2, but at least 5 other genes can cause HNPCC: MLH3, MSH6, TGBR2, PMS1, and PMS2. An abnormal copy of any one of these genes reduces the body's ability to repair damage to its DNA. This results in an increased risk of cancer of the colon and small intestine, as well as a high risk of endometrial and ovarian cancer. People with this syndrome have up to a 4% chance of developing small intestine cancer. This condition is also discussed in our document, Colorectal Cancer.

• 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 many types of cancer, including small intestine adenocarcinoma. This syndrome is caused by mutations in the gene STK1.

• Cystic fibrosis (CF): This condition causes severe lung problems. Often, in someone with CF, the pancreas cannot make the enzymes that break food down so that it can be absorbed. People with CF have an increased risk of adenocarcinoma of the ileum. The gene that causes CF is called CFTR. A child must have 2 abnormal copies of this gene (one from each parent) to get this disease.

Last Medical Review: 08/13/2009
Last Revised: 08/13/2009