The types of small bowel cancer may include:¹

• Adenocarcinoma - begins in glandular cells in the lining of the small bowel
• Neuroendocrine tumours (NETs) - develop from hormone-producing cells in the lining of the small bowel
• Lymphoma - forms in lymph tissue within the small bowel, which is part of the body’s immune system
• Sarcoma - begins in connective tissue that supports and connects structures within the body

Small bowel cancer may cause no symptoms, particularly in its early stages. When symptoms do occur, they are often non-specific and may be similar to those caused by other conditions, which can make diagnosis more difficult.¹

Symptoms may include:¹

• Blood in the stool or dark, tarry stools
• Unexplained weight loss
• Ongoing or recurring abdominal pain
• Nausea and vomiting
• Changes in bowel habits, such as diarrhoea or less commonly constipation
• Tiredness and weakness caused by low red blood cell levels (anaemia)
• A feeling of fullness or a lump in the abdomen (less common)
• Yellowing of the skin or eyes (jaundice), in rare cases

If you experience any of these symptoms, or have ongoing concerns, please contact your GP.

The exact cause of small bowel cancer is not known. However, several factors may increase a person’s risk of developing small bowel cancer, including:¹

• Inherited genetic conditions – certain rare inherited disorders, such as familial adenomatous polyposis (FAP) and Lynch syndrome, can increase the risk of small bowel cancer
• Inflammatory bowel disease – particularly Crohn’s disease affecting the small intestine, which is one of the strongest known risk factors
• Coeliac disease – associated with an increased risk of some types of small bowel cancer, particularly lymphoma
• Dietary factors – a diet high in red or processed meats may be associated with an increased risk, although evidence for small bowel cancer is limited

A range of tests may be used to investigate symptoms and diagnose small bowel cancer. Following a physical examination, further tests may include:¹

• Blood tests – used to check red and white blood cell levels and platelets, which may help identify anaemia or infection. Liver function tests may also be performed. In some cases, a chromogranin A (CgA) blood test may be used to help assess suspected neuroendocrine tumours, although results are not specific
• Endoscopy – involves using a thin tube with a camera to examine the upper digestive tract under sedation. Specialised forms of endoscopy may be used to examine parts of the small bowel
• Capsule endoscopy – involves swallowing a small capsule containing a camera that takes images of the small bowel as it passes through the digestive system. The capsule is passed naturally in the stool, usually within 24 hours
• Imaging scans – may include computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), or less commonly a barium X-ray, to help identify tumours and assess whether cancer has spread
• Biopsy – if an abnormal area is found, a small tissue sample may be taken and examined under a microscope to confirm a diagnosis

Typically the main treatment for most small bowel cancers. Surgery aims to remove the cancer and a surrounding section of healthy tissue. Nearby lymph nodes may also be removed

Chemotherapy uses medicines to destroy cancer cells or slow their growth. Chemotherapy may be used after surgery to reduce the risk of the cancer returning, or when surgery is not possible.

Radiation therapy, Radiation therapy, also called radiotherapy, uses controlled doses of radiation to damage or destroy cancer cells. Treatment is usually delivered from outside the body using a machine called external beam radiation therapy.^2,3

Radiation therapy is used less commonly for small bowel cancer, but may be recommended in some situations to help relieve symptoms or control the growth of the cancer.

Immunotherapy uses medicines to help the immune system recognise and attack cancer cells and may be an option for some people with advanced small bowel cancer, depending on the cancer type and its molecular features.⁴

Targeted therapy uses medicines that target specific features of cancer cells. This treatment may be suitable for some types of small bowel cancer, including certain neuroendocrine tumours.⁴

This focuses on relieving symptoms and improving quality of life. It can be provided at any stage of cancer, alongside other treatments.