The small bowel, which is also called the small intestine, is part of the body’s digestive system. It is a long tube that carries digested food between your stomach and your large intestine (colon).
The small bowel is responsible for:
- digesting and absorbing nutrients from the foods you eat
- producing hormones that help with digestion
- has a role in your body’s germ-fighting immune system, as it contains cells that fight bacteria and viruses that enter your body through your mouth.
Like other cancers, small bowel cancer starts with uncontrolled growth and multiplication of abnormal cells. Over time, these abnormal cells develop into a progressively larger mass which starts to block the small bowel.
What is small bowel cancer
Small bowel cancer (also called small intestine cancer) is an uncommon type of cancer that 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 cells that are affected.
The most common types of small bowel cancer are:
- Adenocarcinoma – this type of tumour starts in epithelial cells – the mucous-releasing cells that line the inside of the small intestine, often in the duodenum.
- Sarcoma – this type of tumour starts in connective tissue (which support and connect all the organs and structures of the body). Gastro-intestinal stromal tumours (GIST) start in nerve cells anywhere in the small intestine. Leiomyosarcoma starts in muscle tissues in the wall of the small intestine, often in the ileum.
- Neuroendocrine tumours (NETs) – 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 – form in lymph tissue (part of the immune system which protects the body) in the small intestine, often in the jejunum. Non-Hodgkin lymphoma starts in lymphocytes, a type of white blood cell.
Causes of small bowel cancer
The cause of small bowel cancer is not known in most cases. However, there are several factors that may increase the risk including:
- Genetic factors – some rare, inherited diseases can put people more at risk of small intestine cancer. Examples include Lynch syndrome, familial adenomatous polyposis (FAP) and Peutz-Jeghers syndrome.2,3
- Other factors:
- some small intestine cancers may be linked to Crohn’s disease and coeliac disease2,3
- eating large amounts of animal fat and protein, especially processed meat and red meat2,3
- smoking2,3
- older age – most people diagnosed with small intestine cancer are over 60 years.2
- Weakened immune system. If your immune system is weakened, you may have an increased risk of small bowel cancer. E.g. HIV infection and those who take anti-rejection medicine after an organ transplant.2,3
Symptoms of small bowel cancer
Early stages of small bowel cancer can often present with no symptoms or non-specific symptoms, which can also be commonly found in other illnesses. This can make it difficult to diagnose.2,3
Most small bowel cancers are diagnosed late at more advanced stages of the disease.2,3
Symptoms may include:2,3
- Blood in stool or on the toilet paper
- Unexplained weight loss
- A lump in the abdomen
- Pain, cramps or swelling in the middle of the abdomen
- Nausea and vomiting
- Change in bowel habit including diarrhoea, constipation, or the feeling of incomplete emptying
- Tiredness and weakness, caused by a low red blood cell count (anaemia)
- Yellowing of the skin and eyes (jaundice).
If you experience any of these symptoms or have concerns, please contact your general practitioner (GP).
