Intestinal cancer causes and risk factors

Intestinal cancer is a growth of cancerous cells in the small intestine, which is part of the digestive system. This long, narrow tube connects the stomach to the large intestine.

Intestinal cancer, also called small intestine cancer, is much less common than other cancers of the gastrointestinal (GI) tract, such as colorectal cancer and stomach cancer. According to the American Cancer Society, fewer than one in 10 GI malignancies are cancers of the small intestine. Across all cancers, small intestine cancer accounts for fewer than one in 100 cases. According to the National Cancer Institute, an estimated 0.3 percent of people in the United States will develop cancer of the small intestine during their lifetime.

What causes intestinal cancer?

While the exact cause of intestinal cancer may not be known, several factors may increase the risk for developing the disease. Statistics show that men are slightly more likely to develop the disease than women. Small intestinal cancer also tends to occur more often in older people and is most often found in people in their 60s and 70s.

Is intestinal cancer hereditary?

Although most small intestine cancers occur without a known hereditary link, some inherited conditions may lead to a higher risk. The inherited conditions associated specifically with small intestine adenocarcinoma are:

• Familial adenomatous polyposis (FAP)
• Hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome
• Peutz-Jeghers syndrome (PJS)
• Cystic fibrosis (CF)
• Multiple endocrine neoplasia, type I (MEN1) or defects in the gene NF1 (type 1 neurofibromatosis) may lead to benign tumors in the small intestine that may become malignant carcinoid tumors.
• Gardner syndrome, caused by a genetic defect, may cause polyps to develop throughout the GI tract, particularly in the colon. Although it poses a greater risk for developing colon cancer, this disease is considered a risk factor for sarcomas of the small intestine.
• Von Recklinghausen's disease, a type of neurofibromatosis, an inherited gene mutation, may lead to gastrointestinal stromal tumors (GISTs). However, there usually is no known cause for GISTs of the small intestine and hereditary links are rare.

Learn more about genetic testing

Intestinal cancer risk factors

General

Age: According to the National Cancer Institute, the average age at diagnosis is 67.

Gender: Men are slightly more likely to develop the disease than women.

Lifestyle

Tobacco and alcohol use: Lots of evidence links cigarette smoking and alcohol abuse to many types cancer. Some research suggests that smoking and drinking may also be associated with small intestine cancer.

Diet: Eating a high-fat diet may be a small intestine risk factor.

Chemical exposure: Certain chemicals, like vinyl chloride, dioxins and high doses of herbicides containing phenoxyacetic acid, are considered intestinal cancer risk factors for certain types of sarcomas, possibly including sarcomas in the small intestine.

Other conditions

Gastrointestinal diseases: Certain diseases that affect the gastrointestinal (GI) tract may increase the risk for developing small intestine cancer. For example, Crohn's disease is a condition in which the immune system harms the small intestine. If the patient has had colon cancer, he or she may also be at an increased risk for small intestine adenocarcinoma, possibly because both cancers share similar risk factors. The GI diseases that are considered risk factors for small intestine cancer are:

• Colon cancer
• Celiac disease
• Crohn's disease

Lymphedema: Damage to the lymph vessels (the vessels that connect the lymph nodes) or an infection may cause lymph fluid to build up. Lymphedema is also sometimes referred to as elephantiasis. This may increase a person's risk of developing a sarcoma of the small intestine.

Next topic: What are the symptoms of intestinal cancer?