Neuroendocrine tumours

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Neuroendocrine tumours at a glance

Neuroendocrine tumours are a varied group of tumours that develop in cells with both nerve-like and hormone-making functions. They often start in the bowel, pancreas or lungs. Some grow slowly over many years; others need treatment promptly. The name alone does not tell you how a particular tumour will behave.

• A neuroendocrine tumour is often shortened to NET. You may also see the older term carcinoid, particularly for some bowel and lung tumours.
• Treatment depends on where the tumour began, how far it has spread, how quickly it is growing and whether it produces hormones that cause symptoms. There is no single treatment plan for all NETs.
• A small tissue sample, taken during a biopsy, usually confirms the diagnosis. A pathologist is a doctor who examines tissue. They look at the cells and test features that help predict how the tumour may behave.
• Surgery may cure a localised NET, meaning one confined to its starting area. Some carefully selected small tumours can be monitored safely. For more widespread disease, several treatments can control growth and symptoms.
• A NET in the pancreas is different from the more common type of pancreatic cancer. A lung carcinoid is also different from small cell lung cancer.
• Symptoms, nutrition and quality of life deserve attention throughout treatment, including when scans show that the tumour is stable.

Questions to ask your doctor first

• Where did my tumour start?
• What is the exact type of tumour?
• What is its grade, and what does this suggest about how quickly it may grow?
• What is its stage, and has it spread?
• Is it causing a hormone syndrome—symptoms from excess hormone activity?
• Does it have somatostatin receptors—docking points that certain scans and treatments can target?

Bring your written scan reports and a compact disc (CD) containing the scan images. Ask the scan centre for images in Digital Imaging and Communications in Medicine (DICOM) format, with the software needed to view them.

Keep your tissue test (pathology) report, previous treatment details, medicine list and an emergency contact number together. For a second opinion, ask whether the team needs your tissue samples, stored on slides or in blocks.

Symptoms that need attention

Possible symptoms include persistent abdominal pain, a change in bowel habits, unexplained weight loss, a persistent cough or repeated chest infections. Some NETs cause flushing (sudden warmth and redness of the skin), watery diarrhoea, wheezing or episodes of low blood sugar. Many other conditions can cause these symptoms, so tests are needed to establish the cause. Some NETs are discovered on a scan performed for another reason.

Seek urgent assessment for severe abdominal pain with vomiting or swelling, inability to keep fluids down, collapse, confusion, severe breathlessness or chest pain. Severe low blood sugar can cause sweating, trembling, unusual behaviour or loss of consciousness. If the person is unconscious, do not give food or drink by mouth; call emergency services.

Understand

What neuroendocrine cells do

Neuroendocrine cells respond to signals and release hormones. Hormones are chemical messengers that help control functions such as digestion and blood sugar. These cells occur in many organs, which is why NETs can arise in different places. A tumour is named after its starting organ even if it later spreads elsewhere. A bowel NET that spreads to the liver remains a bowel NET.

This guide focuses on well-differentiated neuroendocrine tumours, whose cells still look like normal neuroendocrine cells. A separate, usually faster-growing group called neuroendocrine carcinoma is explained where the distinction affects care.

The main groups

Tumours in the digestive tract and pancreas may be grouped as gastroenteropancreatic NETs, shortened to GEP-NETs. This guide does not cover every neuroendocrine-related tumour family, such as phaeochromocytoma, paraganglioma or medullary thyroid cancer; these require their own pathways.

Grade and differentiation explain different things

Differentiation describes how closely the tumour cells look like normal neuroendocrine cells. Grade describes how actively they are growing. For digestive NETs, the pathologist counts dividing cells and uses a test called Ki-67. Its result is the percentage of cells showing a protein linked to growth.

A grade 3 NET is different from a poorly differentiated neuroendocrine carcinoma. Grade 3 also does not mean stage 3. For lung carcinoids, doctors mainly assess dividing cells and areas of cell death; they do not simply use the Ki-67 limits for digestive NETs. If the diagnosis is unclear, an experienced pathologist can review it.

Functioning and non-functioning tumours

A functioning tumour releases enough hormone to cause symptoms. A non-functioning tumour does not cause a hormone syndrome. It can still grow, spread or release substances that tests can detect.

Some bowel NETs cause carcinoid syndrome, usually involving flushing and diarrhoea. Over time, excess hormone activity can damage heart valves in some people. Pancreatic NETs may cause other syndromes: an insulinoma can lower blood sugar, while a gastrinoma can cause excess stomach acid, ulcers and diarrhoea. Treating the hormone problem is often as important as treating tumour growth.

Why NETs happen

Most people have no single identifiable cause. Some NETs occur with an inherited condition, including multiple endocrine neoplasia type 1, often called MEN1, or von Hippel–Lindau disease. These conditions involve gene changes that can increase the risk of several tumours. Genetic counselling helps you understand inherited risk and whether testing may help. It may be appropriate with a pancreatic NET, diagnosis at a young age, several tumours or a personal or family history that suggests inherited risk.

Having a NET does not mean that your children will develop one. There is no routine screening programme for everyone. Regular tests for relatives are arranged when a specific inherited risk has been confirmed.

Tests and diagnosis

Confirming the diagnosis

The team combines your symptoms, examination, scans and tissue results. A biopsy may be taken through the skin with scan guidance, during a camera examination or at surgery. The safest useful site may be the original tumour or a deposit elsewhere.

The pathology report should name the tumour type, describe how its cells look and give the relevant grade. Special laboratory dyes applied to the tissue help identify neuroendocrine cells. If different tumour sites behave differently, or growth suddenly speeds up, the team may review the tissue or take another biopsy. A small sample may not show every feature of the tumour.

Scans and camera tests

Not everyone needs every test. A receptor scan and an FDG scan answer different questions. Some NETs have few somatostatin receptors, so a negative receptor scan does not rule out a NET. Before receptor-targeted treatment, the team checks how much tracer the important tumour sites absorb. This is called uptake. Enough uptake helps select treatment, but does not guarantee it will work.

Before tests, tell the team if you are pregnant or breastfeeding, have kidney disease or an implanted device, or have reacted to contrast dye.

Blood and urine tests

Routine tests check blood counts, kidney and liver function, blood sugar and body salts. Hormone tests are selected according to the symptoms and suspected tumour type.

If carcinoid syndrome is suspected, the team may check blood or urine for 5-hydroxyindoleacetic acid (5-HIAA). The body makes this when it breaks down serotonin, a chemical involved in hormone symptoms. Some foods and medicines affect the result. Follow the laboratory’s instructions and do not stop prescribed medicines without advice.

Chromogranin A is a substance sometimes measured in blood. Its level alone cannot confirm or rule out a NET. Medicines for stomach acid, kidney problems and other conditions can raise it. Your team considers the result alongside symptoms and scans.

Heart assessment and other checks

People with carcinoid syndrome may need a heart scan using sound waves, called an echocardiogram, and blood tests for strain on the heart. Report new ankle swelling, increasing breathlessness or finding activity harder than usual. A dietitian may also check for vitamin shortages or difficulty absorbing food.

Tests for inherited risk and treatment targets

Blood or saliva tests look for gene changes that can run in families. Tumour tests look for changes in the cancer that might help choose treatment. Broader tumour testing may help when cancer is advanced or unusual, especially if standard options are limited. A test finding does not guarantee that a medicine will work or be available.

Planning your treatment

Understanding your stage

Stage describes where the tumour is and whether it has spread. NETs do not share one universal staging chart. The system depends on the starting organ and tumour type.

The commonly used tumour, node and metastasis system, shortened to TNM, describes the original tumour, nearby lymph nodes and spread to distant sites. Lymph nodes are small structures involved in immune defence. Metastasis means cancer has spread from its starting place.

Your team will explain whether the disease is localised, has extended into nearby structures or nodes, or has spread to distant organs. Liver spread is common in some NETs. Even when cure is unlikely, selected well-differentiated NETs may be controlled for a long time. A stage describes the current findings; it is not a sequence that everyone must go through.

How the team chooses a plan

A multidisciplinary team brings together specialists to plan your care. It may include doctors who treat cancer, perform surgery, interpret scans, examine tissue, give radioactive treatments or manage hormone problems. Specialist nurses and a dietitian also help. A heart specialist may join when needed.

The decision considers:

• The starting organ, differentiation, grade and rate of change on scans.
• Whether all important tumour sites show somatostatin receptors.
• The amount and location of disease and whether it threatens an organ.
• Hormone symptoms, nutrition, other illnesses and previous treatments.
• Your priorities, treatment burden, travel, cost and access.

Monitoring can be an active treatment decision

Some small, low-risk tumours can be monitored with planned scans and reviews. This is called surveillance. It may suit selected small, non-functioning pancreatic NETs after specialist assessment. Size alone is not enough: the team also considers growth, changes in the small tubes that drain digestive fluid from the pancreas, symptoms, grade and the risks of surgery. You need a written follow-up schedule and clear reasons to reconsider treatment.

Questions about your treatment

• Is the aim cure, slowing growth, controlling hormones or relieving a particular symptom?
• Why is this treatment preferred now, and what are the alternatives?
• How will we judge benefit, and what would make us change the plan?
• Do I need a specialist NET opinion, genetic counselling or heart assessment?
• What should I do if symptoms worsen between appointments?

Understanding the outlook

Your outlook, sometimes called your prognosis, depends on your particular tumour. The starting site, grade, spread, hormone effects, general health and response to treatment all matter. A single survival figure for all NETs would be misleading. Ask for a realistic range and what information may make that estimate clearer over time.

Treatment options

Surgery and local removal

Surgery offers the main chance of cure when the tumour can be removed completely and safely. The operation depends on where it started. Some small, low-risk NETs in the stomach, duodenum (the first part of the small bowel) or rectum can be removed through an endoscope. Bowel surgery may include nearby lymph nodes. Pancreatic surgery may remove part of the pancreas and sometimes nearby organs. Lung surgery aims to preserve as much working lung as possible.

Not every small tumour needs the same operation. After complete removal of a well-differentiated NET, routine chemotherapy has not generally been shown to prevent the tumour coming back (recurrence). Follow-up remains important because some NETs return years later.

Surgery when a NET has spread needs a separate discussion. It may help selected people when deposits can be removed, the bowel may become blocked, or hormone symptoms are difficult to control. The benefits and risks vary. Removing the starting tumour does not help everyone with widespread disease.

Somatostatin analogue injections

Somatostatin is a natural hormone that reduces the release of several other hormones. Medicines that act similarly are called somatostatin analogues. Octreotide and lanreotide can control hormone symptoms and slow growth in suitable NETs. Long-acting injections are commonly given about every four weeks; short-acting treatment may be used for particular symptoms or procedures.

The choice depends on where the tumour started, its receptors, your symptoms and the evidence for that situation. These injections can cause tummy discomfort, gallstones, blood sugar changes or problems digesting fat. Report oily stools, bloating or weight loss. Some people need pancreatic enzymes—medicines that help digest food.

Peptide receptor radionuclide therapy

Peptide receptor radionuclide therapy, shortened to PRRT, uses a medicine that attaches to suitable receptors on tumour cells and carries radiation to them. One established treatment is lutetium-177 dotatate, also called Lutathera. A receptor scan checks whether the tumour is likely to absorb the treatment.

A specialist nuclear medicine service gives PRRT, usually as four infusions (drips) around eight weeks apart. The schedule may be adjusted. A separate drip containing amino acids, the building blocks of proteins, helps protect the kidneys. The team checks blood counts and kidney and liver function. You receive instructions about drinking fluids, toilets, close contact, pregnancy and breastfeeding while radiation leaves the body.

The team also coordinates the timing of octreotide or lanreotide injections around each treatment. Ask for a written schedule and a plan for hormone symptoms between treatments. Do not stop or reschedule these medicines yourself.

PRRT can cause nausea (feeling sick), tiredness and low blood counts. Less common risks include kidney damage and later disorders of the bone marrow, where blood cells are made. Rarely, these include blood cancers. The team weighs these risks against the expected benefit and your previous treatment.

A research study called NETTER-2 tested PRRT in selected people with newly diagnosed, advanced NETs of the digestive system or pancreas. Their tumours were well-differentiated grade 2 or 3, had a Ki-67 result of 10% to 55%, and showed enough receptor uptake on scans. PRRT with octreotide delayed cancer growth compared with high-dose octreotide alone.

The study did not compare PRRT directly with chemotherapy or targeted medicines. Its results do not apply automatically to poorly differentiated neuroendocrine carcinoma. PRRT is therefore not necessarily the best first treatment for every NET.

Targeted medicines

Targeted medicines interfere with signals that help tumours grow. Relevant options include:

There is no single best order for these treatments. In a study called CABINET, cabozantinib delayed cancer growth in people who had already received treatment. The study did not compare it directly with PRRT, chemotherapy or another targeted medicine. Your team considers previous treatment, likely benefits and side effects.

These are systemic treatments: medicines that travel through the body. Each suits different situations and needs its own safety checks. Side effects may include diarrhoea, a sore mouth, tiredness, and changes in blood pressure or blood tests. Everolimus can also cause infection, high blood sugar and lung inflammation. Sunitinib and cabozantinib can cause sore hands and feet. Bleeding, wound-healing problems and other serious side effects need specific precautions.

Chemotherapy and faster-growing disease

Chemotherapy uses medicines that damage cancer cells. It may be useful when shrinkage is needed or in particular tumour types. Capecitabine with temozolomide is one option often considered for pancreatic NETs; other chemotherapy combinations may suit different situations. This use is supported by disease-specific evidence and guidance and may be outside a medicine's local product licence.

Well-differentiated grade 3 NETs need an individual treatment plan. For selected tumours starting in the pancreas or bowel, other chemotherapy options include:

• FOLFOX: fluorouracil, folinic acid and oxaliplatin.
• CAPOX: capecitabine and oxaliplatin.

The choice depends on the tumour’s features, how quickly it is growing, previous treatment and your general health.

Poorly differentiated neuroendocrine carcinomas are a different group. For advanced digestive neuroendocrine carcinoma, a platinum chemotherapy medicine (carboplatin or cisplatin) with etoposide is commonly used. This combination is not automatically the right choice for a well-differentiated NET. Small cell lung cancer has its own treatment pathway.

Treatments directed at liver deposits

Some tumour deposits in the liver can be removed surgically or destroyed with heat or another local method, called ablation. Other procedures block the blood supply to the deposits. These are called embolisation; some also deliver chemotherapy or radioactive particles. They may help selected people when most disease is in the liver or hormone symptoms are hard to control.

The team considers the amount of liver involved, liver function, disease elsewhere and previous treatments. Fever, pain and nausea can follow a procedure; liver injury is a more serious risk. Liver transplantation is reserved for exceptionally selected patients in specialist programmes.

Radiotherapy, immunotherapy and clinical trials

External-beam radiotherapy directs radiation from a machine. It may relieve pain from bone deposits or treat a troublesome area. Its role differs from PRRT.

Immunotherapy helps the immune system attack cancer. It is not routine treatment for most well-differentiated NETs. It may be considered if testing finds an unusual tumour feature that a treatment can target, or through a clinical trial—a research study involving patients. Trials also test new ways to deliver radiation to tumour cells, combine treatments or choose their order. A promising result alone does not mean a treatment is approved or suitable for routine use.

If the tumour grows during treatment

The team first checks whether the tumour has grown, hormone symptoms have worsened, or something else is causing your symptoms. Options include a different medicine, PRRT, a local procedure, chemotherapy or a trial. Sometimes only a few tumour sites need extra treatment while the main treatment continues to help. Another biopsy may be useful if the tumour’s behaviour changes markedly.

Managing side effects

Hormone symptoms and digestion

Keep a short record of bowel movements, flushing, food intake and symptoms around injections. Diarrhoea may come from hormones, infection, surgery, bile-acid changes, poor fat digestion or treatment. Its cause matters because the treatment differs.

Drink regularly. If diarrhoea is frequent, ask about oral rehydration solution, which replaces lost water and salts. A dietitian can help you maintain weight without unnecessary food restrictions. Some people need digestive enzymes, vitamins or medicine for diarrhoea caused by bile acids, which help digest fat. For eligible adults with persistent diarrhoea from carcinoid syndrome, telotristat may be added to somatostatin analogue treatment. It controls this symptom; it does not replace cancer treatment.

If your tumour causes low blood sugar

Ask for a written plan covering regular meals, blood sugar checks, what to carry for a sudden episode and when to seek emergency help. Family members should know the plan too. Do not fast for a test unless the team has explained how this will be supervised safely.

Planning procedures safely

Before any operation or procedure, tell the team that you have a NET, especially if you have carcinoid syndrome. This includes the anaesthetist—the doctor who gives medicines to keep you comfortable or asleep and monitors you during a procedure. A carcinoid crisis is a sudden, dangerous change in hormone effects, blood pressure and breathing. It can happen around procedures or during severe illness. The team plans monitoring, emergency treatment and any preventive medicines. These precautions cannot remove the risk completely.

Looking after yourself during treatment

Take medicines exactly as prescribed and tell the team about supplements or herbal products. Before treatment, ask about mouth care, anti-sickness medicines and managing diarrhoea. Check blood pressure or blood sugar at home if advised. Report problems early: adjusting a dose may make treatment easier to manage while keeping its benefit.

When to call urgently

Contact the oncology team urgently for fever of 38°C (100.4°F) or higher during chemotherapy, or the lower threshold your team gives you; shaking chills; severe diarrhoea; repeated vomiting; new cough or breathlessness; unusual bleeding; or markedly reduced urine. A serious infection can occur without a high temperature: call promptly if you suddenly feel very unwell. Seek emergency help for collapse, severe chest pain or severe abdominal pain.

Live well

Follow-up and living with a NET

Follow-up may include symptom review, examination, blood tests and scans. The schedule depends on the site, grade, previous treatment and risk of recurrence. Follow-up after surgery can continue for many years. Receptor PET–CT is not necessarily needed at every visit; the team chooses the test that will answer the current question.

Ask for a written plan specifying who arranges scans, who explains results and what symptoms should trigger an earlier review. Do not wait for the next routine appointment if symptoms change substantially.

Food, activity and emotional wellbeing

Aim to maintain muscle and weight with regular meals, enough protein and activity suited to your energy. Diarrhoea, bowel surgery or pancreatic treatment may need individual nutrition advice. There is no proven universal NET diet or supplement that cures the tumour. Avoid very restrictive diets unless a particular medical problem requires them.

Living with uncertainty or long-term treatment can be tiring even when the cancer is controlled. Ask for help with sleep, anxiety, low mood, work and relationships. Supportive and palliative care focus on symptom relief and quality of life alongside active cancer treatment. They are appropriate at any stage, including when treatment aims for long-term control.

Fertility, pregnancy and family life

Discuss pregnancy plans and contraception (preventing pregnancy) before treatment. Some medicines, including radioactive treatments, can harm a developing baby. The safe waiting time before pregnancy depends on the treatment. If having children in future matters to you, ask for fertility advice before treatment starts. Breastfeeding restrictions also vary and can last a long time after radioactive treatment.

For caregivers

It may help to attend key appointments, keep the medicine list current and know the urgent contact route. Agree with the patient how much practical help they want. Look after your own sleep and health, and ask the team for support if caregiving is becoming difficult.

Related care

Related reading

Preparing for your first visit↗Caregiver toolkit↗

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