This map explains small intestine (small bowel) cancer step by step: what it is, the types, the tests, the stages, the treatment and its side effects.
Tap any topic on the map to read about it. Topics with an arrow open more topics.
Several different tumours can start in the small intestine, and they are treated very differently. Tap a type on the map.
Most common in the ileum. Usually slow growing; can cause flushing and diarrhoea (carcinoid syndrome). Neuroendocrine tumours
Lymphoma of the small intestine is treated as a blood cancer, mainly with chemotherapy. Blood cancers
Tap a test on the map to see why it is done.
Please wait for all the reports. Why we wait
Special CT or MRI scans with drinkable contrast to show the small bowel, plus CT of the chest, abdomen and pelvis to check for spread.
A tumour marker, used to follow treatment.
Before starting chemotherapy, immunotherapy or targeted therapy, these tests check that you are fit for treatment, and give a starting point to compare with later.
| Test | Why it is done |
|---|---|
| CBC (complete blood count) | Haemoglobin, white cells and platelets. Treatment can lower them. |
| RFT (kidney function) | Many medicines are cleared by the kidneys; the dose may need to change. |
| LFT (liver function) | Many medicines are processed by the liver. |
| Viral markers: HBsAg, anti-HCV, HIV | Hepatitis B can flare up during treatment. If positive, a tablet is given to prevent this. |
| Blood sugar (and HbA1c if diabetic) | Steroids given with chemotherapy can raise blood sugar. |
| ECG and 2D Echo | Check the heart rhythm and pumping before treatment, as some medicines affect the heart. |
Before immunotherapy, also:
| Test | Why it is done |
|---|---|
| Serum TSH (thyroid) | Immunotherapy can affect the thyroid gland. |
| Serum cortisol (morning sample) | Immunotherapy can affect the adrenal and pituitary glands. |
Sometimes needed, depending on your treatment:
Your doctor will choose the tests that apply to you. Some of them are repeated during treatment.
The stage is worked out from scans and, after surgery, the removed tissue. Tap your stage on the map.
Grown into the inner layers of the bowel wall. No lymph nodes. The aim is cure.
Grown through the bowel wall. No lymph nodes. The aim is cure.
Spread to nearby lymph nodes. The aim is cure.
Spread to other organs such as the liver or peritoneum. Usually not curable; treatment controls it.
Because this cancer is rare, much of the treatment is based on studies in colon cancer. Tap your stage on the map.
Side effects: surgery · chemotherapy
Side effects: surgery · chemotherapy
Your doctor will advise MMR testing and NGS. Why
Side effects: chemotherapy · immunotherapy
Tap a treatment on the map.
Vomiting with a swollen tummy and no stools or wind (possible blockage), black or bloody stools, severe tummy pain, jaundice, or fever of 38°C or more need urgent care.
This information is general. Your own treatment plan may be different. Please discuss it with your doctor.
Written and medically reviewed by Dr Prathyusha Eaga, MD, DM (Medical Oncology). Last reviewed: 12 October 2026. Based on NCCN and ESMO guidelines.
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