What is the small bowel?

The small bowel is part of the digestive system between the stomach and large bowel. It helps your body to digest food and absorb vitamins and is between 4 and 6 metres long.

The small bowel is made up of:

  • the duodenum (the top part which connects to the stomach)
  • the jejunum (the middle part)
  • the ileum (the lower part which connects to the large bowel)

What are the different types of small bowel cancer?

There are four main types of small bowel cancer:

  • Adenocarcinoma: This is the most common type of small bowel cancer and is most often found in the duodenum (duodenal cancer)
  • Lymphomas: These start in the lymph tissue, which is part of the body’s immune system. Small bowel lymphomas are most often found in the ileum and are usually non-Hodgkin lymphomas
  • Neuroendocrine tumours: These start from cells that make hormones in the small bowel, usually in the ileum
  • Sarcoma: This starts in the supportive tissues of the body and the most common is gastrointestinal stromal tumour (GIST), which can develop anywhere in the small bowel. There are also leiomyosarcomas, which usually start in the muscle wall of the ileum

Cancer can also spread to the small bowel from somewhere else, which is known as a secondary cancer. Large bowel, skin, lung and breast cancers are the types that most commonly spread to the small bowel.


The main symptoms of small bowel cancer are:

  • abdominal pain
  • weight loss
  • nausea and vomiting
  • diarrhoea
  • tiredness
  • dark or black poo (due to bleeding)


The causes of small bowel cancer are not fully understood, but the following conditions can increase a person’s risk of small bowel cancer:

Diagnosis and treatment

The hospital may arrange the following tests to diagnose small bowel cancer:

  • blood tests
  • stool sample
  • barium meal
  • CT scan
  • MRI scan
  • endoscopy
  • capsule endoscopy

Treatment may depend on where the cancer is, its size, whether it has spread to other parts of the body, and other individual factors for each person. Small bowel treatments can include surgery and chemotherapy.



* Statistics from Cancer Research UK and Macmillan, accessed 03.06.24