Small intestine cancer is a rare disease in which malignant (cancer) cells form in the tissues of the small intestine.

The small intestine is part of the body’s digestive system, which also includes the esophagus, stomach, and large intestine. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The small intestine is a long tube that connects the stomach to the large intestine. It folds many times to fit inside the abdomen.

There are five types of small intestine cancer.

The types of cancer found in the small intestine are adenocarcinoma, sarcoma, neuroendocrine tumors, gastrointestinal stromal tumor, and lymphoma. This summary discusses adenocarcinoma and leiomyosarcoma (a type of sarcoma).

Adenocarcinoma starts in glandular cells in the lining of the small intestine and is the most common type of small intestine cancer. Most of these tumors occur in the part of the small intestine near the stomach. They may grow and block the intestine.

Leiomyosarcoma starts in the smooth muscle cells of the small intestine. Most of these tumors occur in the part of the small intestine near the large intestine.

For more information on small intestine cancer, see the following:

• Gastrointestinal Neuroendocrine Tumors Treatment
• Gastrointestinal Stromal Tumors Treatment

Diet and health history can affect the risk of developing small intestine cancer.

Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop small intestine cancer, and it will develop in some people who don't have any known risk factors. Talk with your doctor if you think you may be at risk. Risk factors for small intestine cancer include the following:

• Eating a high-fat diet.
• Having Crohn disease.
• Having celiac disease.
• Having familial adenomatous polyposis (FAP).

Signs and symptoms of small intestine cancer include unexplained weight loss and abdominal pain.

These and other signs and symptoms may be caused by small intestine cancer or by other conditions. Check with your doctor if you have any of the following:

• Pain or cramps in the middle of the abdomen.
• Weight loss with no known reason.
• A lump in the abdomen.
• Blood in the stool.

Tests that examine the small intestine are used to diagnose and stage small intestine cancer.

Procedures that make pictures of the small intestine and the area around it help diagnose small intestine cancer and show how far the cancer has spread. The process used to find out if cancer cells have spread within and around the small intestine is called staging.

In order to plan treatment, it is important to know the type of small intestine cancer and whether the tumor can be removed by surgery. Tests and procedures to detect, diagnose, and stage small intestine cancer are usually done at the same time. In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:

• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.
• Liver function tests: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by the liver. A higher than normal amount of a substance can be a sign of liver disease that may be caused by small intestine cancer.
• Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. There are different types of endoscopy:
  • Upper endoscopy: A procedure to look at the inside of the esophagus, stomach, and duodenum (first part of the small intestine, near the stomach). An endoscope is inserted through the mouth and into the esophagus, stomach, and duodenum. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.
  • Capsule endoscopy: A procedure to look at the inside of the small intestine. A capsule that is about the size of a large pill and contains a light and a tiny wireless camera is swallowed by the patient. The capsule travels through the digestive tract, including the small intestine, and sends many pictures of the inside of the digestive tract to a recorder that is worn around the waist or over the shoulder. The pictures are sent from the recorder to a computer and viewed by the doctor who checks for signs of cancer. The capsule passes out of the body during a bowel movement.
  • Double balloon endoscopy: A procedure to look at the inside of the small intestine. A special instrument made up of two tubes (one inside the other) is inserted through the mouth or rectum and into the small intestine. The inside tube (an endoscope with a light and lens for viewing) is moved through part of the small intestine and a balloon at the end of it is inflated to keep the endoscope in place. Next, the outer tube is moved through the small intestine to reach the end of the endoscope, and a balloon at the end of the outer tube is inflated to keep it in place. Then, the balloon at the end of the endoscope is deflated and the endoscope is moved through the next part of the small intestine. These steps are repeated many times as the tubes move through the small intestine. The doctor is able to see the inside of the small intestine through the endoscope and use a tool to remove samples of abnormal tissue. The tissue samples are checked under a microscope for signs of cancer. This procedure may be done if the results of a capsule endoscopy are abnormal. This procedure is also called double balloon enteroscopy.
• Laparotomy: A surgical procedure in which an incision (cut) is made in the wall of the abdomen to check the inside of the abdomen for signs of disease. The size of the incision depends on the reason the laparotomy is being done. Sometimes organs or lymph nodes are removed or tissue samples are taken and checked under a microscope for signs of disease.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. This may be done during an endoscopy or laparotomy. The sample is checked by a pathologist to see if it contains cancer cells.
• Upper GI series with small bowel follow-through: A series of x-rays of the esophagus, stomach, and small bowel. The patient drinks a liquid that contains barium (a silver-white metallic compound). The liquid coats the esophagus, stomach, and small bowel. X-rays are taken at different times as the barium travels through the upper GI tract and small bowel.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis and treatment options depend on the following:

• The type of small intestine cancer.
• Whether the cancer is in the inner lining of the small intestine only or has spread into or beyond the wall of the small intestine.
• Whether the cancer has spread to other places in the body, such as the lymph nodes, liver, or peritoneum (tissue that lines the wall of the abdomen and covers most of the organs in the abdomen).
• Whether the cancer can be completely removed by surgery.
• Whether the cancer is newly diagnosed or has recurred.