Symptoms of small bowel cancer include:

• Abdominal pain.
• Yellowing of the skin and the whites of the eyes, called jaundice.
• Feeling very weak or tired.
• Nausea.
• Vomiting.
• Losing weight without trying.
• Blood in the stool, which might look red or black.
• Watery diarrhea.
• Skin flushing.

The cause of small bowel cancer isn't known. What's known is that something happens to cells in the small bowel that changes them into cancer cells.

Small bowel cancer happens when cells develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. The changes tell the cells to multiply quickly. The cells continue living when healthy cells would die as part of their natural life cycle. This causes too many cells. The cells might form a mass called a tumor. The cells can invade and destroy healthy body tissue. In time, the cells can break away and spread to other parts of the body.

Types of small bowel cancer

The type of small bowel cancer you have is based on the type of cell where your cancer began. Examples of small bowel cancer types include:

• Adenocarcinoma. Adenocarcinoma is the most common type of small bowel cancer. Adenocarcinoma starts in the gland cells that make mucus.
• Neuroendocrine tumors. Neuroendocrine tumors are cancers that start in the neuroendocrine cells. Neuroendocrine cells are found in many places in the body. They do some nerve cell functions and some of the work of cells that make hormones.
• Lymphoma. Lymphoma is a cancer that starts in immune system cells. The body's immune system fights germs. Immune system cells in the small intestine fight bacteria and viruses that enter the body through the mouth. Most lymphomas in the small bowel are a type of non-Hodgkin's lymphoma.
• Soft tissue sarcoma. Soft tissue sarcomas are cancers that start in the body's connective tissues. One type of soft tissue sarcoma is a gastrointestinal stromal tumor, also known as GIST. GIST starts in special nerve cells that are found in the wall of the small bowel.

Your health care team considers your type of small bowel cancer when creating a treatment plan.

Factors that may increase the risk of small bowel cancer include:

• DNA changes that run in families. Some DNA changes that are passed down from your parents can increase your risk of small bowel cancer and other cancers. Examples include Lynch syndrome, familial adenomatous polyposis, also called FAP, and Peutz-Jeghers syndrome.
• Other bowel diseases. Other diseases and conditions that affect the intestines may increase the risk of small bowel cancer. These may include 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 medicine to control the immune system after an organ transplant.
• What you eat and drink. Some studies have found a higher risk of small bowel cancer in those who eat and drink certain things. For example, the risk seems to be associated with drinking alcohol and eating a diet that's low in fiber and high in red meat, sugar, and salt-cured and smoked foods.

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. These may include those that affect the colon, rectum, ovaries and the lining of the uterus, called the endometrium.
• Cancer that spreads to other parts of the body. Advanced small bowel cancer can spread to other parts of the body. When cancer spreads, it's called metastatic cancer. Small bowel cancer most often spreads to the liver.

It's not clear what may help to reduce the risk of small bowel cancer. 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 different vitamins and nutrients.
• Drink alcohol in moderation, if at all. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
• Stop smoking. Talk to a health care professional 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 health care team 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 health care team 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.

Small bowel cancers are difficult to diagnose. For this reason, people suspected of having small bowel cancer often need multiple tests and procedures to locate the cancer or rule out a cancer. These may include:

• Blood tests. Blood tests can't detect small bowel cancer, but they can give clues about your health. A blood test called a complete blood count can detect a low red blood cell count. The red blood cells could be low if small bowel cancer is causing bleeding. Blood tests also can show how well the organs are working. For example, results on kidney or liver function tests could be a clue that the cancer has spread to those organs.
• Imaging tests. Imaging tests create pictures of the body. They can show the location and size of small bowel cancer. Tests might include MRI, CT and positron emission tomography, also called a PET scan.
• Removing a sample of tissue for testing, also called a biopsy. A biopsy is a procedure to remove a sample of tissue for testing in a lab. The tissue might be removed during a procedure to see inside the small intestine. During this type of procedure, special tools can be put into the small intestine to collect the sample. Sometimes surgery is needed to get the tissue sample. The sample is tested in a lab to see if it is cancer. Other special tests give more details about the cancer cells. Your health care team uses this information to make a treatment plan.

Tests to see inside your small intestine

Several tests allow doctors to examine the inside of the small intestine. Often, a sample of tissue is collected during these tests. Which test you need depends on where in the small intestine your cancer is located. Options include:

• Upper endoscopy. Upper endoscopy is a procedure to look at the inside of the esophagus, stomach and first part of the small intestine. A thin, tube-like instrument with a light and a lens for viewing, called an endoscope, is inserted through the mouth and passed down the throat. Tools are passed through the tube to remove a sample of tissue for testing.
• Capsule endoscopy. In a capsule endoscopy, also called a pill camera, a pill-sized capsule that has a camera and a light is swallowed. It takes pictures as it moves through the digestive system. The capsule then exits the body during a bowel movement. This test can't collect a sample of tissue for testing. If something is found on a capsule endoscopy, you might need other tests to find out what it is.
• Enteroscopy. Enteroscopy uses special devices to guide an endoscope into the small intestine. It helps doctors to see more of the small intestine than can be seen with upper endoscopy. A tissue sample might be collected during enteroscopy. To get to the cancer, the scope may be passed down the throat or through the rectum and colon. How your enteroscopy is performed will depend on the cancer's location. Sometimes you need medicine to put you in a sleep-like state during enteroscopy.

Surgery

Sometimes small bowel cancers are in places that make them hard to see with other tests. If this happens, your health care team may suggest surgery to look at your small intestine and the surrounding area for signs of cancer.

Surgery can involve one large incision in your abdomen, called a laparotomy. It also can involve several small incisions, called a laparoscopy. During laparoscopy, a surgeon passes special tools through the incisions, as well as a video camera. The camera allows the surgeon to guide the tools and see inside your abdomen. The tools may be used to collect a sample of tissue for testing. Often, the cancer is removed during this procedure.

Treatment for small bowel cancer usually involves surgery to remove the cancer. Other options might be chemotherapy and radiation therapy. Your health care team considers the location of your cancer and its type when creating a treatment plan. They also consider your overall health and your preferences.

Small bowel cancer treatments might include:

• Surgery. Surgeons work to remove all of the small bowel cancer, when possible. If cancer affects a small part of the small intestine, the surgeon may remove only that section. The surgeon then rejoins the cut ends of the intestine. Sometimes all of the small intestine needs to be removed. The surrounding lymph nodes also may be removed to see if there is a risk of the cancer spreading.

  If a small bowel cancer can't be removed, a surgeon might perform a bypass to relieve a blockage in the small intestine.

• Chemotherapy. Chemotherapy uses strong medicines to kill cancer cells. Chemotherapy usually involves a combination of medicines that kill fast-growing cells, including cancer cells. It's typically given through a vein, but some medicines come in pill form.

  For small bowel cancer, chemotherapy might be used after surgery if there's a risk that the cancer could return. For advanced cancer, chemotherapy might help relieve symptoms. If the cancer is too big to be removed with surgery, it may first be treated with chemotherapy to shrink it.

• Radiation therapy. Radiation therapy uses powerful energy beams to kill cancer cells. The energy can come from X-rays, protons or other sources. During radiation therapy, you lie on a table while a machine moves around you. The machine directs radiation to precise points on your body. Radiation therapy is sometimes combined with chemotherapy before surgery to shrink the size of the cancer.
• Targeted therapy. Targeted therapy uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die. Targeted therapy might be used for small bowel cancer when surgery isn't an option or when the cancer spreads to other parts of the body.
• Immunotherapy. Immunotherapy is a treatment with medicine that helps your body's immune system to kill cancer cells. Your immune system fights off diseases by attacking germs and other cells that shouldn't be in your body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells. Immunotherapy might be an option for advanced small bowel cancer if testing shows the cancer cells may respond to this type of treatment.

With time, you'll find what helps you cope with the uncertainty and distress of a small bowel cancer diagnosis. Until then, you may find it helps to:

• Learn enough about small bowel cancer to make decisions about your care. Ask your health care team about your cancer, including your test results, treatment options and, if you like, your prognosis. As you learn more about small bowel cancer, you may become more confident in making treatment decisions.
• Keep friends and family close. Keeping your close relationships strong will help you deal with your small bowel cancer. Friends and family can provide the practical support you'll need, such as helping take care of your home if you're in the hospital. And they can serve as emotional support when you feel overwhelmed by cancer.

• Find someone to talk with. Find someone who is willing to listen to you talk about your hopes and fears. This may be a friend or family member. The concern and understanding of a counselor, medical social worker, clergy member or cancer support group also may be helpful.

  Ask your health care team about support groups in your area. Other sources of information include the National Cancer Institute and the American Cancer Society.

Make an appointment with a doctor or other health care professional if you have any symptoms that worry you. If your health care team suspects you might have cancer, you may be referred to a specialist.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fasting before having a specific test. Make a list of:

• Your symptoms, including any that might not seem related to the reason for your appointment.
• Key personal information, including major stresses, recent life changes and family medical history.
• All medicines, vitamins or other supplements you take, including the doses.
• Questions to ask your health care team.

Consider bringing a family member or friend to help you remember the information you're given.

For small bowel cancer, some basic questions you might ask include:

• What's likely causing my symptoms?
• Other than the most likely cause, what are other possible causes for my symptoms?
• What tests do I need?
• What's the best course of action?
• What are the alternatives to the primary approach you're suggesting?
• I have these other health conditions. How can I best manage them together?
• Are there restrictions I need to follow?
• Should I see a specialist?
• Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Be prepared to answer questions about your symptoms, such as:

• When did your symptoms begin?
• Have your symptoms been continuous or occasional?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?