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Small Bowel

This information should not be used for self-diagnosis or in place of a qualified physician’s care.

Reviewed 2016

The basics
  • Guidelines for treating this cancer have been developed by the Gastrointestinal (GI) Tumour Group.
  • For health professional information on treating this cancer, please see our Cancer Management Guidelines.
  • Other names/types of small intestine cancers are: small bowel cancer, small intestinal cancer, small intestine adenocarcinoma, gastrointestinal carcinoid tumour, small intestine lymphoma, small intestine liposarcoma, small intestine angiosarcoma, small intestine neurofibrosarcoma, small intestine leiomyosarcoma and gastrointestinal stromal tumour.
  • The small intestine is a tube that connects the stomach to the large intestine.
  • It is the largest part of the gastrointestinal tract. It is about one inch in diameter and about 15 to 20 feet long.
  • It consists of three parts: the duodenum (connected to the stomach), the jejunum (the middle part) and the ileum (connected to the large intestine).
  • Most of the digestion of food takes place in the small intestine.

What causes it and who gets it?

Listed below are some of the known risk factors for this cancer. Not all of the risk factors below may cause this cancer, but they may be contributing factors. 

  • Cancer of the small intestine is quite rare.
  • About 60% of people who get small intestine cancer are men. [See note, Statistics]
  • Small intestine cancer is more common in people over 45.
  • Eating large amounts of animal proteins and fat, refined carbohydrates, red meat, and salt-cured or smoked foods may increase the risk of small intestine cancer.
  • The presence of a Helicobacter pylori infection may increase the risk of small intestine cancer.
  • Having Crohn's Disease or Celiac Disease increases the risk of small intestine cancer.
  • Those with inherited disorders such as Familial Adenomatous Polyposis (FAP), Hereditary Nonpolyposis Colorectal Cancer (HNPCC), Peutz-Jeghers Syndrome (PJS) and Cystic Fibrosis (CF) are at higher risk for small intestine cancer.
  • There is also a small increase in risk for those who have had radiation therapy for cancer of the cervix.
  • Statistics
    NOTE:  Available statistics do not have information about the inclusion of transgender and gender diverse participants. It is unknown how these statistics apply to transgender and gender diverse people.  Patients are advised to speak with their primary care provider or specialists about their individual considerations and recommendations.

Can I help to prevent it?

  • Eating healthy, nutritious foods can reduce your cancer risk. Follow the recommendations in Canada's Food Guide and visit the BC. Cancer Agency’s Prevention page on Nutrition for information and resources. In particular, avoiding large amounts of animal proteins and fat, refined carbohydrates, red meat, and salt-cured or smoked foods can reduce your risk for this cancer. 
  • Eat a gluten-free diet if you have celiac disease. This seems to decrease the risk of small intestine cancer.

Screening for this cancer

No effective screening program exists for this cancer yet.

People who are at higher than average risk of developing small intestine cancer, especially people with Familial Adenomatous Polyposis (FAP), may need to be tested so that if cancer develops it will be found at an early stage. Our Hereditary Cancer Program has more information. 

Signs and Symptoms

  • Non-specific symptoms may delay the diagnosis of small intestine cancer until the cancer has reached an advanced stage
  • Pain or cramps in the abdomen is a common symptom
  • Nausea or vomiting
  • Gastrointestinal bleeding
  • Unexplained weight loss
  • Lump in the abdomen
  • Obstruction of the bowel
  • Anemia
  • Blood in stool
  • Diarrhea
  • Jaundice
Diagnosis & staging


These are tests that may be used to diagnose this type of cancer: 

  • Blood tests
  • Barium X-ray
  • CT scan
  • Angiography
  • Endoscopy
  • Wireless capsule endoscopy
  • Laparotomy

For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests section.

Types and Stages


  • Adenocarcinoma
    • Adenocarcinoma is the most common type of small intestine cancer.
    • It starts in the glandular cells in the lining of the small intestine.
  • Lymphoma
    • 14% of small bowel tumours are lymphomas.
    • Most are non-Hodgkin's lymphomas.
  • Carcinoid tumours
    • Carcinoid tumours are slow-growing cancers that grow in hormone-producing (endocrine) cells in the lining of the intestine.
    • These tumours account for 30% of small bowel malignancies.
  • Gastrointestinal Stromal Tumour (GIST)
    • 85% of tumours formerly called leiomyosarcomas are now known to be GISTs. GISTs start in cells that are part of the autonomic nervous system in the wall of the intestine. About 50 people are diagnosed with GIST in BC per year. Some GISTs are benign.
  • Sarcoma
    • Sarcomas are slow-growing tumours that account for 11% of small bowel cancers.
    • Types of sarcomas include:
      • liposarcomas – start in the fat cells
      • angiosarcomas – start in the blood vessels
      • neurofibrosarcomas – start in the nerves
      • leiomyosarcomas - start in the smooth muscles of the small intestine

Staging describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general, a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment. 

  • T describes the site and size of the main tumour (primary)
  • N describes involvement of lymph nodes
  • M relates to whether the cancer has spread (presence or absence of distant metastases)
  • Stage 0
    In situ disease only. The cancer has not spread through the inner layers of the small intestine. 
  • Stage I 
    The cancer has grown through the inner layers of the small intestine, but has not spread into nearby tissue or lymph nodes. 
  • Stage II 
    The cancer has spread through the wall of the small intestine, but has not spread to the nearby lymph nodes. 
  • Stage III 
    The cancer has spread to lymph nodes, but it has not spread to other parts of the body. 
  • Stage IV
    The cancer has spread to other parts of the body.


Cancer therapies can be highly individualized – your treatment may differ from what is described below. 


  • Adenocarcinomas are usually treated by surgery.
  • If the tumour cannot be removed, surgery may be done to bypass an obstruction or relieve bleeding.
  • Chemotherapy is only recommended for a tumour that cannot be surgically removed or for cancer that has spread.

Lymphoma (see also information about Lymphomas)

  • Surgery of small intestine lymphoma is not recommended, unless necessary for a definite diagnosis or to control the complications of bleeding or perforation.
  • Lymphomas are usually treated by radiation and/or combination chemotherapy.


  • Surgery offers the best chance of cure.
  • Some patients with large tumours may undergo surgery to reduce the tumour, plus chemotherapy.
  • Drugs may be given to relieve the side effects of the excessive hormones produced by the tumour.

Sarcoma and GIST (see also information about Sarcomas)

  • Sarcomas and gastrointestinal stromal tumours should be referred to BC Cancer for management. Sarcomas are usually treated by surgery. If the tumour cannot be removed, surgery may be done to bypass an obstruction or relieve bleeding. When tumours cannot be removed surgically, radiation therapy may be helpful to control bleeding or pain.

Follow-up after Treatment

  • Guidelines for follow-up after treatment are covered on our website.
  • You will be returned to the care of your family doctor or specialist for regular follow-up. If you do not have a family doctor, please discuss this with your BC Cancer oncologist or nurse.
  • Follow-up testing is based on your type of cancer and your individual circumstances.
  • Life after Cancer focuses on the issues that cancer survivors can face.
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