Small Intestine Cancer Facts

Small intestine cancers are rare. About 12,000 people will get this type of cancer in the United States this year, according to the American Cancer Society.

How small intestine cancer develops

Getting small intestine cancer means abnormal cells in that section of your gastrointestinal tract are growing and dividing at a rapid pace — so fast that cells in your immune system that fight disease cannot keep up. There are five types of small intestine cancer that differ depending on the type of cell affected including:

  • Adenocarcinoma is the most common type of small intestine cancer; it starts in the cells that make the mucus lining on the inside of the small intestine and most often develops at the junction of the small intestine and the stomach.
  • Leiomyosarcomas are rare cancers that start in smooth muscle cells in the wall of the small intestine, most often appearing near the large intestine.
  • Carcinoid tumors start in hormone-making cells in the intestine.
  • Gastrointestinal stromal tumors (GISTs) start in special cells found in the wall of the GI tract, called the interstitial cells of Cajal.
  • Lymphomas are a type of cancer that typically start in immune system cells, but can also start in intestinal organs.

What increases your risk of small intestine cancer?

Things that put you at higher risk for getting small intestine cancer are called risk factors. Your risk of getting small intestine cancer depends on a complex interaction between lifestyle factors and your inherited risks — in other words, the ones you’re born with.

Risk factors for small intestine cancer include:

  • Age: Advancing age increases risk for small intestine cancer.
  • Sex: This type of cancer is more often diagnosed in men.
  • Race: Being African-American increases risk.
  • Smoking and drinking alcohol excessively, increase risk.
  • Having had colon cancer increases risk of developing small intestine cancer.
  • Having a history of Crohn’s disease.
  • Having a history of Celiac disease.

Inherited risks for small intestine cancer include familial adenomatous polyposis, Peutz-Jeghers syndrome, MUTYH-associated polyposis, hereditary nonpolyposis colorectal cancer and cystic fibrosis.

If your family history suggests an increased risk of this type of cancer, City of Hope’s Division of Clinical Cancer Genetics offers genetic counseling and screening that can identify whether inherited conditions influence your risk — and guide you to the best treatments.

Small intestine cancer symptoms

The first symptoms related to small intestine cancer tends to be abdominal pain, which can worsen as the tumor grows larger. Typical small intestine cancer symptoms include:

  • pain in the abdomen (belly)
  • dark or bright red blood in the stool                    
  • unintended weight loss
  • an abdominal lump

These symptoms could also be a result of other conditions. Still, if you have any of these problems for more than two weeks, it’s important to see your doctor right away to pinpoint and treat the cause.