Small bowel cancer is an uncommon type of cancer that occurs in the small intestine. Your small intestine, which is also called the small bowel, is a long tube that carries digested food between your stomach and your large intestine (colon).
The small intestine is responsible for digesting and absorbing nutrients from the foods you eat. It produces hormones that help with digestion. The small intestine also plays a role in your body's germ-fighting immune system, as it contains cells that fight bacteria and viruses that enter your body through your mouth.
Types of small bowel cancer include:
- Neuroendocrine tumors, including carcinoid tumors and paraganglioma
- Sarcoma, including gastrointestinal stromal tumor (GIST)
What treatment options are best for you depend on the type of small bowel cancer you have and its stage.
Signs and symptoms of small bowel cancer include:
- Abdominal pain
- Yellowing of the skin and the whites of the eyes (jaundice)
- Feeling unusually weak or tired
- Losing weight without trying
- Blood in the stool, which might appear red or black
- Watery diarrhea
- Skin flushing
Doctors aren't certain what causes most small bowel cancers.
In general, small bowel cancer begins when healthy cells in the small bowel develop changes (mutations) in their DNA. A cell's DNA contains a set of instructions that tell a cell what to do.
Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell's DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren't needed. As these cells accumulate, they form a tumor.
With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can spread (metastasize) to other parts of the body.
Factors that may increase the risk of small bowel cancer include:
- Gene mutations passed through families. Some gene mutations that are inherited from your parents can increase your risk of small bowel cancer and other cancers. Examples include Lynch syndrome, familial adenomatous polyposis (FAP) and Peutz-Jeghers syndrome.
- Other bowel diseases. Other diseases and conditions that affect the intestines may increase the risk of small bowel cancer, including Crohn's disease, inflammatory bowel disease and celiac disease.
- Weakened immune system. If your body's germ-fighting immune system is weakened, you may have an increased risk of small bowel cancer. Examples include people with HIV infection and those who take anti-rejection medicine after an organ transplant.
Small bowel cancer can cause complications, including:
- An increased risk of other cancers. People who have small bowel cancer run a higher risk of having other types of cancers, including those that affect the colon, rectum, ovaries and the lining of the uterus (endometrium).
- Cancer that spreads to other parts of the body. Advanced small bowel cancer can spread (metastasize) to other parts of the body, most often the liver.
It's not clear what may help to reduce the risk of small bowel cancer, since it's very uncommon. If you're interested in reducing your risk of cancer in general, it may help to:
- Eat a variety of fruits, vegetables and whole grains. Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants, which may help reduce your risk of cancer and other diseases. Choose a variety of fruits and vegetables so that you get an array of vitamins and nutrients.
- Drink alcohol in moderation, if at all. If you choose to drink alcohol, limit the amount of alcohol you drink to no more than one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger.
- Stop smoking. Talk to your doctor about ways to quit that may work for you.
- Exercise most days of the week. Try to get at least 30 minutes of exercise on most days. If you've been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your doctor before starting any exercise program.
- Maintain a healthy weight. If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. If you need to lose weight, ask your doctor about healthy ways to achieve your goal. Aim to lose weight slowly by increasing the amount of exercise you get and reducing the number of calories you eat.