What is small bowel cancer?
Small bowel cancer (also called small intestine cancer) occurs when cells in the small bowel become abnormal and keep growing and form a mass or lump called a tumour. The type is defined by the particular cells that are affected.
The most common types of small bowel cancer are:
- Adenocarcinoma. These start in epithelial cells (which release mucus) that line the inside of the small bowel, often in the duodenum.
- Sarcoma. These start in connective tissue (which support and connect all the organs and structures of the body). Gastro-intestinal stromal tumours (GIST) starts in nerve cells anywhere in the small bowel. Leiomyosarcoma starts in muscle tissues in the wall of the small bowel, often in the ileum.
- Neuroendocrine (carcinoid) tumours (NETs) These form in neuroendocrine cells inside the small bowel, often in the ileum. The neuroendocrine system is a network of glands and nerve cells that make hormones and release them into the bloodstream to help control normal body functions.
- Lymphoma. These form in lymph tissue (part of the immune system which protects the body) in the small bowel, often in the jejunum. Non-Hodgkin lymphoma starts in lymphocytes, a type of white blood cell.
It is estimated that more than 900 people were diagnosed with small bowel cancer in 2022. The average age at diagnosis is 67 years old.
Small bowel cancer signs and symptoms
Small bowel cancer can be difficult to diagnose, and symptoms may be vague and caused by other conditions.
Symptoms may include:
abdominal (tummy) pain
unexplained weight loss
a lump in the abdomen
blood in the stools
change in bowel habit including diarrhoea, constipation or the feeling of incomplete emptying
nausea (feeling sick) or vomiting
tiredness and weakness, caused by a low red blood cell count (anaemia)
yellowing of the skin and eyes (jaundice).
Causes of small bowel cancer
The cause of small bowel cancer is not known in most cases. However, there are several risk factors:
Genetic factors – Some rare, inherited diseases can put people more at risk of small bowel cancer.
Other factors – Some small bowel cancers may be linked to Crohn’s disease and coeliac disease. Eating large amounts of animal fat and protein, especially processed meat and red meat, might increase the risk of small bowel cancer. .
Diagnosis of small bowel cancer
If your doctor thinks that you may have small bowel cancer, they will perform a physical examination and carry out certain tests.
If the results suggest that you may have small bowel cancer, your doctor will refer you to a specialist who will carry out more tests. These may include:
You will have blood tests including a full blood count to measure your white blood cells, red blood cells, platelets, and liver function tests to measure chemicals that are found or made in your liver.
You may also have a chromogranin A (CgA) blood test to help diagnose a carcinoid or other neuroendocrine tumour.
In an endoscopy a flexible tube with a camera on the end (endoscope) is inserted under sedation down your throat into the stomach to view your gut.
In a capsule endoscopy you swallow a small capsule that takes pictures of your digestive tract. These are then transmitted to a recorder you wear around your waste. The camera is passed out in your stools after about 24 hours.
Special machines are used to scan and create pictures of the inside of your body. You may have an injection of dye into your veins before the scan which makes the pictures clearer. During the scan you will lie on a table which moves in and out of the scanner. A CT scan takes about 10-30 minutes.
An MRI scan produces detailed cross-sectional pictures of your body and can show the extent of any tumours. You will lie on a table which slides into a large metal tube that is open at both ends. An MRI scan takes about 30-90 minutes.
Before having the PET scan you will be injected with a small amount of radioactive solutions. You will be asked to sit for 30-90 minutes so the solution can mover around your body. Many cancer cells will show up brighter on the scan. The scan takes around 30 minutes.
If your doctor sees any abnormal or unusual-looking areas they may remove a small sample of the tissue for closer examination. This is known as a biopsy. A pathologist will look at the sample under a microscope to check for signs of disease or cancer.
For this procedure you will be given a chalky barium liquid to drink which coats the inside of the bowel and can show any signs of cancer when an x-ray is taken.
Treatment for small bowel cancer
Discussion with your doctor will help you decide on the best treatment for your cancer depending on the type of cancer you have; where it is in your body; whether or not the cancer has spread; your age, fitness and general health and your preferences.
The main treatments for small bowel cancer include surgery and chemotherapy. Often medications are used that block cancer cells from secreting hormones and chemicals. These treatments can be given alone or in combination.
Surgery is the main treatment for small bowel cancer (adenocarcinoma, sarcoma and neuroendocrine tumours), especially for people with early-stage disease who are in good health. It is not usually recommended for lymphomas in the small bowel – these are commonly treated with radiation therapy and/or chemotherapy.
If part of the bowel is removed during surgery, the surgeon will usually join it back together. This join is called an anastomosis. If this isn’t possible, you may need a stoma which can be temporary or permanent.
Chemotherapy is the use of drugs to kill or slow the growth of cancer cells. You may have one chemotherapy drug, or a combination of drugs.
Your treatment will depend on your situation and the type of cancer you have. Chemotherapy is often used to treat lymphomas in the small bowel. Your medical oncologist will discuss your options with you.
Immunotherapy or biological therapy uses the body’s own immune system to fight cancer. It uses materials made either by the body or in a laboratory to improve immune system function. There are different types of immunotherapy available so talk to your doctor about what might be appropriate for you.
Radiation therapy (radiotherapy)
Radiation therapy (also known as radiotherapy) uses high energy rays to destroy cancer cells, where the radiation comes from a machine outside the body. It may be used for small bowel cancer:
- before or after surgery, to destroy any remaining cancer cells and stop the cancer coming back
- if the cancer can’t be removed with surgery
- if the cancer comes back in a limited way, such as only in your abdominal lymph glands. Radiation therapy can shrink the cancer down to a smaller size. This may help to relieve symptoms such as pain or blood loss.
In some cases of small bowel cancer, your medical team may talk to you about palliative care. Palliative care aims to improve your quality of life by alleviating symptoms of cancer.
As well as slowing the spread of small bowel cancer, palliative treatment can relieve pain and help manage other symptoms. Treatment may include radiotherapy, chemotherapy or other drug therapies.
Treatment TeamDepending on your treatment, your treatment team may consist of a number of different health professionals, such as:
- Cancer nurse - assists with treatment and provides information and support throughout your treatment.
- Medical oncologist - prescribes and coordinates the course of chemotherapy.
- Physiotherapist/occupational therapist- help with physical and practical problems such as restoring movement and mobility after treatment.
- Surgeon- surgically removes tumours and performs some biopsies.
- GP (General Practitioner) - looks after your general health and works with your specialists to coordinate treatment.
- Radiation oncologist - prescribes and coordinates radiation therapy treatment.
- Other allied health professionals - such as social workers, pharmacists, and counsellors
- Dietitian - recommends an eating plan to follow while you are in treatment and recovery.
- Gastroenterologist - specialises in diseases of the digestive system..
Screening for small bowel cancer
There is currently no national screening program for small bowel cancer available in Australia.
Preventing small bowel cancer
The cause of most small bowel cancer is not known, however limiting your intake of red and processed meat may reduce your risk.
Prognosis of small bowel cancer
It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person's individual circumstances. However, your doctor may give you a prognosis - the likely outcome of the disease - based on the test results, the rate of tumour growth, as well as your age, fitness and medical history.
Understanding Small Bowel Cancer. Cancer Council Australia © 2021. Last medical review of this source fact sheet: 2021.
Australian Institute of Health and Welfare (AIHW). Cancer in Australia 2019. Cancer series no.119. Cat. no. CAN 123. AIHW, Canberra, 2019.
Australian Institute of Health and Welfare. Cancer data in Australia. Canberra: AIHW, 2022.
This web-based resource was made possible by the Cancer Australia Supporting people with cancer Grant initiative, funded by the Australian Government.
This information was last updated January 2023.