The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on September 21, 2021.

About intestinal cancer

Intestinal cancer occurs when cancer cells form in the small intestine (or small bowel). When cancer develops in the large intestine (also called the large bowel or colon), it is called colon cancer. The small intestine connects the stomach to the large intestine. Shaped like a long tube, the small intestine is divided into three sections: the duodenum, jejunum and ileum. Most types of small intestine cancer develop in the duodenum.

The American Cancer Society estimates approximately 11,390 people in the United States will be diagnosed with small intestine cancer in 2021.

What causes intestinal cancer?

The cause of small intestine cancer is not well understood. Some diseases, practices and inherited conditions that are risk factors for the disease include:

  • Family history of familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC, also called Lynch syndrome), Peutz-Jeghers syndrome (PJS) or cystic fibrosis (CF)
  • Multiple endocrine neoplasia, type 1 (MEN1) or defects in the gene NF1 (type 1 neurofibromatosis)
  • Gardner syndrome
  • Von Recklinghausen’s disease
  • Smoking tobacco and drinking alcohol
  • High-fat diet
  • Chemical exposure to toxins such as vinyl chloride, dioxins and high doses of herbicides containing phenoxyacetic acid
  • Colon cancer
  • Celiac disease
  • Crohn's disease
  • Lymphoma (also known as elephantiasis)

Learn about risk factors for intestinal cancer

Who gets intestinal cancer?

Statistics show that intestinal cancer risk is slightly higher for men than women. Nearly a third of all cases are diagnosed in patients older than 65, and the average age of diagnosis is 67.

People who smoke or drink alcohol, who have gastrointestinal conditions or cancers or who have certain inherited diseases are at increased risk of developing intestinal cancer.

Intestinal cancer types

Intestinal cancer, also called small intestine cancer or small bowel cancer, usually starts in the lining of the small intestine and may spread from the digestive system to other parts of the body. Most cases of intestinal cancer develop in the duodenum, or upper part of the small intestine.

The main types of cancer in the small intestine include:

  • Adenocarcinomas, which usually form in the cells that line the walls of the small intestine, often developing out of small, benign (noncancerous) growths called polyps
  • Sarcomas, which develop in the connective tissue of the small intestine
  • Gastrointestinal stromal tumors, which are variants of soft-tissue sarcoma
  • Carcinoid tumors, also called neuroendocrine tumors, which form in the lining of the intestines and are often slow-growing
  • Lymphomas, which may originate in the intestines

Learn more about intestinal cancer types

Intestinal cancer symptoms

Tumors in the small intestine may block the flow of food and affect digestion. As the tumor gets bigger, the blockages may cause pain in the abdomen. A slowly bleeding tumor may lead to anemia. Digested blood may cause the stool to become black or tarry. An obstruction—when the flow of food is completely blocked—may cause intense pain, nausea and vomiting and typically requires immediate surgery.

In general, however, intestinal cancer symptoms are often vague and difficult to diagnose. Small tumors in an early stage may not cause apparent symptoms until the cancer spreads, making early detection difficult. High-risk patients should develop a cancer prevention plan that involves regular screenings.

The common symptoms of intestinal cancer include:

  • Abdominal pain
  • Unexplained weight loss
  • Weakness or fatigue
  • Bloody or tarry bowel movements
  • A noticeable lump in the abdomen

Learn more about intestinal cancer symptoms

Diagnosing intestinal cancer

Tools and procedures used for intestinal cancer screening and diagnosis include:

  • Upper gastrointestinal (GI) series
  • Endoscopic procedures
  • Enteroclysis
  • Barium enema with X-rays
  • Computerized tomography scan (CT scan)

Learn about diagnostic procedures for intestinal cancer

Intestinal cancer treatments

Common treatment options for intestinal cancer may include:

  • Surgery, such as the Whipple procedure to remove parts of several gastrointestinal organs, or palliative procedures such as those used to insert a small tube to bypass a blockage caused by a tumor in the digestive tract
  • Chemotherapy
  • Radiation therapy, including sophisticated forms of intensity modulated radiation therapy (IMRT)

Learn about treatment options for intestinal cancer