Insulinoma
Insulinomas are rare neuroendocrine tumours (NETs). They start in the insulin making cells of the pancreas. These cells are called islet cells. So insulinomas are also called islet cell tumours.
Neuroendocrine tumours (NETs) are a group of neuroendocrine cancers. Doctors also use the term neuroendocrine neoplasm (NEN) for neuroendocrine cancer.
NETs start in 
and can develop in different parts of the body.
NETs can be slow or fast growing. The cancer cells look abnormal. But they still have some similarities to normal neuroendocrine cells.
In the pancreas, neuroendocrine cells make different types of hormones. These hormones help the body to break down food. Insulinomas make the hormone insulin. Insulin controls the amount of sugar (glucose) in the blood.
Doctors sometimes group NETs depending on whether they make and release abnormal levels of hormones:
- Non-functioning NETs make and release normal levels of hormones.
- Functioning NETs make and release abnormal levels of hormones.
This page is about insulinomas. These are a type of functioning NET that develop in the pancreas.
They are also called gastro entero pancreatic neuroendocrine tumours (GEP NETs) or pancreatic neuroendocrine tumours (pNETs).
The pancreas
The pancreas is part of our .
The pancreas is quite high up in the tummy (abdomen). It lies across your body where the ribs meet at the bottom of the breastbone, just behind your stomach. It is about 6 inches long (15 centimetres) and shaped like a leaf.
The pancreas has 3 parts:
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the wide part is the head
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the thin end is the tail
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the part in the middle is the body
The pancreatic duct is a tube that collects the digestive juices made by the pancreas. It carries them into the first part of the bowel (duodenum).
The pancreas makes digestive juices. And it makes different types of hormones such as insulin.
Insulin is a hormone that controls the amount of sugar (glucose) in the blood. It helps glucose to move from the blood into body cells. This reduces the amount of glucose in the blood and lowers the blood sugar level
How common is an insulinoma?
Insulinomas are very rare. Only between 1 and 3 people in every million develop an insulinoma every year.
Although rare, insulinoma is the most common type of functioning pancreatic NET.
Symptoms of insulinoma
Insulinomas make the hormone insulin. Insulin controls the amount of blood sugar in the body
The most common symptoms of insulinomas are caused by changes in the blood sugar level. You usually have symptoms when your blood sugar is low.
Having low levels of blood sugar can be dangerous if you don’t eat something straight away. You might have fits (seizures) and become unconscious (coma).
Other symptoms include:
- weakness and tiredness
- headaches
- problems with your eyes
- forgetfulness and confusion
- behaving in a way which isn’t normal for you
- hunger and sickness
- sweating and tremors
- palpitations
Whipple’s triad
The Whipple’s triad is a collection of symptoms that help doctors diagnose an insulinoma. It includes:
- symptoms of a low blood sugar such as feeling dizzy and sweating
- a blood sugar level lower than 2.2 mmol per litre of blood
- feeling better after eating food with a high amount of sugar, or after having a glucose drip
You should see your doctor if you have any symptoms that are unusual for you. Or if symptoms won’t go away, or are getting worse. Although your symptoms are unlikely to be cancer, it is important to get them checked by a doctor.
Seeing your GP and referral to a specialist
You might see your GP because of symptoms caused by changes in the levels of insulin. Insulinomas are rare. So your doctor might ask you to have tests that check for other conditions first.
Your GP looks at your symptoms and will decide what specialist to refer you to. They might refer you to an endocrinologist if you have problems with your blood sugar levels. Endocrinologists are doctors who specialise in conditions that affect the system.
If you have an insulinoma, your specialist will refer you to a neuroendocrine cancer team. They might ask you to have more tests.
Tests for insulinoma
Tests are to check the type of cancer you have. Tests also show the size of the cancer and whether it has spread. This helps your doctor plan your treatment.
Tests might include:
- checking your blood sugar level
- a fasting test
a CT scan an MRI scan - an
endoscopic ultrasound scan of your tummy to look at your stomach, pancreas and bile ducts, and to take biopsies - radioactive scans - these include specialised PET scans
A fasting test is to check if your blood sugar levels go down if you don’t eat. You stay in hospital having regular blood tests to check your blood sugar levels. You can drink water but not eat or drink anything else for up to 72 hours.
Grades and stages of insulinoma
Grade
The looks at a sample of insulinoma cells under a microscope. They look at:
- how abnormal the cancer cells look – doctors call this differentiation
- how quickly or slowly they are dividing and growing – this is grading
Insulinomas are well differentiated cancers. This means the NET cells look abnormal. But they still have some similarities to normal neuroendocrine cells.
There are 3 grades of insulinomas – grade 1, 2 and 3. Grade 1 are slow growing and grade 3 are the fastest growing. Grade 2 grow at a moderate rate.
Stage
You have tests to find out the size of the insulinoma and whether it has spread. This is your stage. Doctors use your stage to plan your treatment.
There are different ways to stage pancreatic NETs. Doctors usually use the TNM system or number stages. There are 4 main stages of pancreatic NETs - stage 1 to stage 4.
Risks and causes
A risk factor is anything that increases your risk of getting a disease.
We don’t know what causes most neuroendocrine cancers. But there are some risks factors that can increase your risk of developing it. Having one of these risk factors doesn’t mean that you will definitely develop a cancer.
The risk factors for pancreatic NETs include:
- an inherited condition called multiple endocrine neoplasia 1 (MEN1)
- having a family history of cancer
Treatment for insulinoma
Surgery is the main treatment for insulinomas. But surgery is not always possible. Some insulinomas might have already started to spread. Or you may not be well enough to have an operation.
You might have other treatments if surgery isn’t an option.
Deciding which treatment you need
A team of doctors and other professionals discuss the best treatment and care for you. They are called a multidisciplinary team (MDT).
The treatment you have depends on:
- where the NET is and its size
- how many tumours you have
- whether it has spread to other parts of the body
- your general health and fitness
- the symptoms you have
Your doctor will discuss your treatment. And tell you about its benefits and the possible side effects.
You are likely to have a clinical nurse specialist (CNS). They go to the MDT meetings. They can help answer your questions and support you. They are often your main point of contact throughout your treatment.
Types of treatment for insulinoma
It helps to be aware of the symptoms of a low blood sugar level. Symptoms include:
- headaches
- double or blurred vision
- confusion and dizziness
- tiredness
- sweating
- constantly feeling hungry
Symptoms of insulinoma can be difficult to cope with. To help control your blood sugar levels, you might have:
- a high sugar (glucose) diet
- drugs to reduce the amount of insulin you make
A high sugar (glucose) diet
Insulinomas make too much insulin, which lowers the level of blood sugar in your body. To help control the blood sugar, you need to have sugary drinks and snacks. And have lots of small meals throughout the day. Your doctor or dietitian can tell you what types of food you should eat.
Drugs to reduce the amount of insulin you have
Some drugs can help to control the blood sugar level by reducing the amount of insulin you make. The most common drug used is diazoxide.
Other drugs that can help to control the blood sugar levels are verapamil, diphenylhydantoin and steroids such as prednisolone.
Surgery to remove the insulinoma is usually the main treatment.
Some of these are major operations and there are risks. But if the aim is to try to cure the NET, you might feel it is worth some risks. Talk to your doctor about the risks and benefits of your surgery.
There are different types of surgery. The type of operation you have depends on several factors. These include:
- where the cancer is in your pancreas
- the size of your cancer
There are different ways of doing the operation:
- Open surgery means the surgeon makes a large cut (incision) in your tummy.
Keyhole or laparoscopic surgery means your surgeon makes some small incisions in your tummy. They put a laparoscope and other small instruments through these to remove the cancer. It is also called minimally invasive surgery.
How you feel and how quickly you recover depends on the type of surgery you have. Your surgeon will be able to tell you more about what to expect.
There are different operations:
Enucleation means the surgeon removes just the tumour. They leave the healthy pancreatic tissue behind.
A distal pancreatectomy means the surgeon removes:
- the narrowest part of the pancreas
- the body of the pancreas
A pylorus preserving pancreaticoduodenectomy (PPPD) means the surgeon removes:
- the widest part of the pancreas
- the duodenum
- the gallbladder
- part of the bile duct
A Whipple’s operation means the surgeon removes:
- the widest part of the pancreas
- duodenum
- gallbladder
- part of the bile duct
- part of the stomach
If the cancer has spread to the liver, your surgeon might remove the liver tumours at the same time as the main surgery. Your surgeon may remove just the tumour or part of the liver.
Your surgeon might suggest they remove all of your pancreas if you have a rare family syndrome. These syndromes are or . This is because people with these syndromes are likely to develop more NETs in the rest of the pancreas.
Radiofrequency ablation uses heat made by radio waves to kill cancer cells. You might have this if you are too unwell to have surgery and the insulinoma is only in the pancreas.
You might have other treatments if:
- you can’t have surgery to remove the NET
- the NET has spread to another part of the body
- the NET came back after the initial treatment
These treatments can control your symptoms and help you feel better but won’t get rid of the NET. There are a number of different treatment options:
somatostatin analogues - drugs include octreotide and lanreotide- peptide receptor radionuclide therapy (PRRT) - this uses a radioactive medicine to treat the NET
chemotherapy – drugs include temozolomide, fluorouracil, capecitabine, streptozotocintargeted cancer drugs – drugs include everolimus and sunitinib
For cancer that has spread to your liver you might have:
- trans arterial embolisation (TAE) to cancer in your liver
radiofrequency ablation - surgery to remove cancer from your liver
- a liver transplant – this is a rare treatment for NETs
Doctors are always trying to improve treatments and reduce the side effects. As part of your treatment, your doctor might ask you to take part in a clinical trial. This might be to test a new treatment or to look at different combinations of existing treatments.
Follow up
You usually have follow up appointments after treatment. This is to check how you are and see whether you have any problems or worries.
You might also have tests on some visits. The tests might include:
- blood tests
- an MRI or CT scan
How often you see your doctor depends on:
- the grade of your NET
- whether it has spread to other parts of the body
- what treatment you have had
- any side effects you might have
It is important you contact your doctors if you have any worrying symptoms between appointments.
Get in touch with your doctors if you have any symptoms of a low blood sugar.
Survival (prognosis) for insulinoma
The best person to talk to you about your outlook () is your doctor. Not everyone wants to know. People cope differently with cancer and want different information.
Survival depends on many factors. So no one can tell you exactly how long you will live. Your doctor might be able to give you some guide, based on their knowledge and experience.
Your prognosis will depend on the type of NET you have and what it is.
Coping with neuroendocrine cancer
You might have physical changes to your body because of your cancer or the treatment. These changes can be hard to cope with and can affect the way you feel about yourself. It can help to talk to friends and family. Or join a support group to meet people in a similar situation.
We have a discussion forum called Cancer Chat. It is a place for anyone affected by cancer. You can share experiences, stories and information with other people with cancer.
You might need practical advice about benefits or financial help. There is help and support available. There are also organisations to support and provide information to people affected by neuroendocrine cancer.
