What is multiple endocrine neoplasia type 2 (MEN2)?

There are 2 types of multiple endocrine neoplasia. They are MEN1 and MEN2. Although their names are similar, they are separate conditions. This information is about MEN2.

Your body is made up of tiny building blocks called cells. Inside every cell is a set of genes. These are the instructions the cell needs to work normally. Sometimes the structure of a gene is permanently changed. The change is called a gene variant or alteration. Doctors sometimes use the term gene mutation. It means the gene no longer gives the correct instructions.

People with MEN2 have a RET gene variant. If you have this variant, you are more likely to develop certain types of tumour.

What tumours are caused by MEN2?

MEN2 causes tumours that usually affect endocrine glands. Endocrine glands produce hormones. Hormones act as chemical messengers and control many functions in the body.

The endocrine glands most likely to be affected by MEN2 are:

  • the thyroid gland, which is in the front of the neck
  • the adrenal glands, which are on top of the kidneys
  • the parathyroid glands, which are in the front of the neck.

Tumours caused by MEN2 can be cancerous (malignant) or non-cancerous (benign). Malignant tumours can spread to other parts of the body.

Some tumours cause an overproduction of hormones in the gland they are affecting.

Types of MEN2

There are 2 types of MEN2:

  • MEN2A is the most common type. 95 in 100 (95%) are this type.
  • MEN2B is sometimes called MEN3. Only 5 in 100 (5%) are this type.

MEN2A can be divided further into 4 subtypes:

  • classical MEN2A
  • MEN2A with a skin condition called cutaneous lichen amyloidosis – this is very rare
  • MEN2A with a bowel condition called Hirschsprung disease – this is very rare
  • familial medullary thyroid cancer (FMTC) but no history of phaeochromocytoma or hyperparathyroidism.

MEN2A and MEN2B both cause a higher risk of a specific type of thyroid cancer called medullary thyroid carcinoma (MTC).

People with MEN2A may also develop:

  • a tumour of the adrenal gland called phaeochromocytoma
  • overactive and enlarged parathyroid glands.

People with MEN2B may also develop:

  • a tumour of the adrenal gland called phaeochromocytoma
  • benign tumours (neuromas) on the lips, tongue and lining of the mouth, and in the bowel.

How MEN runs in families

Genes are passed from parent to child (inherited) when a sperm and egg join to start a pregnancy (conception).

How genes are inherited

Parent and child figures are used to show how 4 combinations of genes can be made from 1 sperm and 1 egg. 2 of the combinations contain a gene variant carried by 1 parent.
Image: The image shows a female and male figure. A pair of genes is shown beside each figure. The female has two green genes shown side by side. The male figure has a green gene and a red gene shown side by side. The red gene is the gene variant. Below the female, two circles are shown. These are two eggs. Each egg contains a copy of one of the female’s genes. Below the male, two ovals with tails are shown. These are two sperm. Each sperm contains a copy of one of the male’s genes. One sperm contains the green gene. The other sperm contains the red gene variant. Lines travel down from each egg and sperm to four child figures. The lines show which genes have passed from an egg and a sperm to each child. Four possible combinations of genes can be made using one of the eggs and one of the sperm. Two of the children have two green genes. They have a copy of a green gene from one of the eggs and a copy of the green gene from the sperm. Two children have a green gene and a red gene variant. They have a copy of a green gene from one of the eggs and a copy of the red gene mutation from the other sperm.

We have 2 copies of each gene – 1 from our mother and the other from our father:

  • the sperm contains 1 copy of the father’s genes
  • the egg contains 1 copy of the mother’s genes.

You only get 1 copy of each of your parent’s genes. If 1 parent has a gene variant, you either get the copy containing the variant, or you do not. This means there is a 1 in 2 (50%) chance you inherit the variant.

A small number of people are the first in their family to have the RET gene variant. This means your parents did not have it. But any children you have will have a 1 in 2 (50%) chance of inheriting it from you.

We have more information about how genes are passed on.

Diagnosing MEN2

Symptoms will depend on which endocrine gland is affected. They are usually related to the thyroid gland. Some people only have mild symptoms.

Symptoms usually occur at a young age. They may occur in teenagers or young adults but can occur in children. Symptoms of MEN2 can vary, even between members of the same family.

You are likely to be diagnosed with MEN2 if:

  • you have 2 or more tumours commonly linked to MEN2 caused by a RET gene variant
  • you have 1 tumour linked to MEN2, and a member of your family has MEN2
  • a genetic test shows you have a RET gene variant.

If you have a tumour that could be caused by MEN2, your doctors will arrange further tests to check for other tumours. They will also check whether other family members may have had MEN2 tumours.

Genetic testing

If your doctor thinks you may have MEN2, you may be offered genetic testing. This involves having a blood test. Your blood is checked to see if you have the RET gene variant.

Your specialist doctor will explain:

  • what your genetic testing result shows
  • how this may affect your health
  • how this may affect other people in your family.

If the blood test shows you have a RET gene variant, you will be referred to a genetics specialist.

Screening and tests for MEN2 tumours

You may have some of the tests below to find the cause of particular symptoms.

The tests can also be used to check for MEN2 tumours before you have any symptoms. This is called screening or monitoring. Screening helps your doctor find and treat tumours at an early stage, usually before symptoms begin to cause problems. The earlier someone knows they have MEN2, the sooner they can have treatment and monitoring to help prevent problems.

You usually have these tests at the hospital and go home on the same day (an outpatient appointment).

  • Blood tests

    Blood tests are used to check the levels of different hormones and chemicals in your body.

  • 24-hour urine collection

    This test may be done to check for adrenal gland tumours. Your pee (urine) will be tested to measure the level of hormones called catecholamines. People with adrenal gland tumours usually produce too much of these hormones.

  • Biopsy

    A biopsy is when a doctor takes a sample of cells or tissue from a part of the body. The sample is then looked at under a microscope to look for changes in the cells.

  • Ultrasound scan

    An ultrasound scan uses sound waves to build up a picture of the organs inside the body.

  • CT scan

    A CT scan takes a series of x-rays that build up a 3D picture of the inside of the body.

  • MRI scan

    An MRI scan uses magnetism to build up detailed pictures of your body. 

  • MIBG scan

    People who may have an adrenal gland tumour may be offered this scan. It involves having an injection of I-123-MIBG. This is mildly radioactive iodine, which is absorbed by adrenal cells. The body is then scanned to check for areas that have absorbed the iodine.

    The dose of radiation from the scan is very low. It is about the same amount you get from an x-ray. Almost all the radiation leaves your body within a week. If you are planning to travel abroad within 3 months of the scan, let the doctor in the scanning department know. They can give you a letter to show to customs officials. This is because ports and airports have very sensitive radiation detectors which may detect tiny amounts of radiation.

Treating MEN2 tumours

A team of specialists meet to talk about the best treatment for you. They are called a multidisciplinary team (MDT).

The MDT look at national treatment guidelines or the latest evidence for the type of cancer you have. If you have any treatment preferences, your doctor will tell them about this.

The MDT will usually include the following professionals:

  • an endocrinologist – a doctor who treats problems with the endocrine system and hormones
  • an endocrine surgeon – a surgeon who operates on endocrine glands
  • an oncologist – a doctor who treats people with cancer
  • a clinical geneticist – a doctor with specialist experience in hereditary conditions
  • a radiologist – a doctor who looks at scans and x-rays to diagnose problems
  • a pathologist – a doctor who looks at changes in the cells of tumours
  • a specialist endocrine nurse – a nurse who can give you support and information about living with MEN2.

Your treatment will depend on the type of tumour, where it is and how early it was diagnosed. You may need surgery to remove tumours and drugs to control symptoms.

Your doctors will talk to you about the best way to manage any tumours. They will discuss your treatment options and explain any tests you might need to monitor your health during and after treatment.

Your doctors may ask you to take part in a clinical trial to find out more about MEN2 and to look at new treatments. They will talk to you about the trial so you fully understand what it involves. You can choose not to take part or leave the trial at any stage. You will still get the standard treatment available.

Medullary thyroid carcinoma (MTC)

What is medullary thyroid carcinoma (MTC)?

MTC is a cancer of the thyroid gland. It is the most common tumour caused by MEN2. Most people with MEN2 will develop MTC unless they have an operation to remove the thyroid at an early age.

The thyroid is a small gland in the front of the neck, just below the voicebox (larynx). It is made up of 2 parts called lobes. The thyroid produces the following hormones:

  • thyroxine (T4)
  • triiodothyronine (T3)
  • calcitonin.

Thyroxine and triiodothyronine keep the body functioning at its normal rate. Calcitonin helps control the amount of calcium in the blood.

The thyroid

The thyroid
Image: This image shows the position of the thyroid gland. It is in the lower middle part of the neck, shaped a bit like a butterfly. The thyroid gland is made up of two lobes, the left lobe and the right lobe. Below the thyroid gland is the windpipe. Either side of the thyroid gland, and under the chin are some lymph nodes. The nodes are joined together by fine tubes called lymph vessels.

Signs and symptoms of MTC

The signs and symptoms of MTC include:

  • a painless lump in the neck
  • difficulty breathing or swallowing – this is due to the tumour pressing on the windpipe (trachea) or gullet (oesophagus)
  • feeling hot and having a red face (flushing)
  • loose poo (stools) or diarrhoea.

Diagnosing MTC

You will have an ultrasound scan of your neck to check the thyroid gland. Your doctor will also check the lymph nodes in your neck to see whether any are abnormal. This is because thyroid cancer can sometimes spread to the lymph nodes. Lymph nodes drain fluid from the tissues and help the body fight infections.

The doctor will take a biopsy from any abnormal areas that show on the scan. They gently pass a small needle into the area and withdraw some cells into a syringe. This is called a fine needle aspiration cytology (FNAC).

You will have a blood test to check the level of calcitonin in your blood. You will also usually have a 24-hour urine test.

Treating MTC

The main treatment for MTC is surgery to remove the thyroid gland. This is called a thyroidectomy. The surgeon will usually also remove nearby lymph nodes.

Some people may not be able to have an operation – for example, if the MTC has spread. In this case, they may have treatment with radiotherapy. Radiotherapy uses high-energy rays called radiation to treat cancer. It destroys cancer cells in the area where the radiotherapy is given.

Some people may also have the targeted drugs vandetanib or cabozantinib. Targeted drugs work by blocking signals in the thyroid cancer cells that make them grow and divide. These treatments cannot cure MTC, but they may help control it.

Preventing MTC

Almost everyone with MEN2 will develop MTC. Because of this, children and young adults with the RET gene variant will usually have surgery to remove the thyroid gland before a cancer develops. Children with MEN2A may have surgery before they are 5 years old. Babies with MEN2B may have surgery before they are 1 year old.

Follow-up for MTC

After the thyroid gland is removed, you will need to take thyroid hormone tablets (levothyroxine) every day for the rest of your life. These replace the thyroid hormones your body needs to function. You will have regular blood tests to check your thyroid hormones are at the right level.

You will also have blood tests to check the levels of calcitonin and a protein called CEA. These blood tests are used to look for any signs of the MTC coming back after surgery.


What is phaeochromocytoma?

Phaeochromocytoma is a tumour of the adrenal gland. It is usually benign.

The adrenal glands are on top of the kidneys.

Position of the kidneys, bladder and adrenal glands

Position of the kidneys, bladder and adrenal glands
Image: The image is a view of the front of the body and shows the position of the kidneys and bladder. There are 2 kidneys – one on the left and one on the right. The kidneys are at waist height. On top of each kidney there is an adrenal gland. The adrenal glands are about a third of the size of the kidney. There is a tube from each kidney going to the bladder. These tubes are the ureters. The bladder is in the front of the body between the hips.

A phaeochromocytoma can develop in people with MEN2A or MEN2B. It may affect 1 or both adrenal glands. Phaeochromocytoma can cause the adrenal gland to make large amounts of hormones called catecholamines. One of these hormones is adrenaline (epinephrine). Adrenaline regulates the heart rate and blood pressure. Having too much adrenaline can cause symptoms such as:

  • severe headaches
  • a fast heart rate (palpitations)
  • excessive sweating
  • feeling anxious
  • increased appetite
  • feeling sick
  • trembling hands
  • pain in the chest or tummy area (abdomen).

Diagnosing phaeochromocytoma

If your doctors think you might have a phaeochromocytoma, you might have the following tests:

  • a blood test or 24-hour urine test, to check the levels of catecholamines in the body
  • a CT or MRI scan of the tummy area (abdomen), to check the kidneys and adrenal glands
  • an MIBG scan, although this is less common than a CT or MRI scan.

Your doctors will tell you about any other tests you might need.

Treating phaeochromocytoma

The main treatment for phaeochromocytoma is an operation to remove the affected adrenal gland.

Before you have the operation, you will need to take a drug called an alpha blocker. This to help control your blood pressure. You will start this as soon as you have been diagnosed with a phaeochromocytoma. Before your operation, you will take a higher dose of the drug. This can cause temporary side effects, including a stuffy feeling in the nose and dizziness when standing. You will be encouraged to drink plenty of fluids during this time.

The operation is usually done using keyhole (laparoscopic) surgery. The surgeon makes 3 to 4 small cuts (incisions) in the side of your tummy or back. They put a tube with a camera on the end (laparoscope) and special surgical tools through the small cuts. They use these tools to remove the tumour. The surgeon may remove a larger tumour through 1 larger incision in the tummy.

You may have 1 or both adrenal glands removed. If just 1 adrenal gland is removed, the other gland will gradually make enough of the hormones your body needs. You will have blood or urine tests every year to check the adrenal gland is healthy.

Sometimes the surgeon will take nearly all of the adrenal glands but leave enough behind to keep the normal function of the adrenal gland. You may still need to take hormone replacement tablets.

If you have both adrenal glands removed, you will need to take hormone replacement tablets every day for the rest of your life.


Overactive parathyroid glands

What are overactive parathyroid glands?

There are 4 parathyroid glands. They are just behind the thyroid gland or sometimes inside it. This is in the front of the neck.

If you have MEN2A, the parathyroid glands may become large and overactive. This is most likely to happen between the ages of 20 to 40.

The thyroid and parathyroid glands

The thyroid and parathyroid glands
Image: The illustration shows the position of the 4 parathyroid glands. They are on the surface of the thyroid gland. The thyroid is in the lower middle part of the neck. The windpipe is shown below the thyroid gland.

Parathyroid glands make a hormone called parathyroid hormone (PTH). PTH helps control calcium levels in the body. People with overactive parathyroid glands may make too much PTH. This can cause your bones to release calcium from the bones into the blood. A high level of calcium in the blood is called hypercalcaemia.

High levels of calcium in the blood can make you:

  • feel sick (nauseous)
  • thirsty
  • drowsy
  • confused
  • unwell
  • constipated
  • need to pee (pass urine) often.

If hypercalcaemia is not treated, the bones get thinner due to loss of calcium. This can lead to osteoporosis. This can cause bone pain, and your bones can break more easily.

High levels of calcium in the blood may also affect the kidneys. Some people develop kidney stones or their kidneys may become damaged. Most people are treated early, so this is not usually a problem.

You will have a blood test every year to check your calcium and PTH levels. It is important to tell your doctor if you have any symptoms that may be caused by high levels of calcium in between screening tests.

Treating overactive parathyroid glands

The main treatment for overactive parathyroid glands is an operation to remove some or all of the parathyroid glands.

If the surgeon needs to remove all of your parathyroid glands, you will need to take tablets for the rest of your life. This is to control calcium levels.

If the surgeon only removes some of the parathyroid glands, the remaining glands can sometimes become overactive after surgery. If this happens, you may need another operation to remove the affected parathyroid glands.

Your surgeon will explain the different treatments for overactive parathyroid glands. You can then decide together what is right for you.

Your doctor may give you drugs called calcimimetic agents to reduce symptoms of overactive parathyroid tissue. They reduce the amount of parathyroid hormone made by the glands.


Neuromas are benign growths. In people with MEN2B, they may develop on the:

  • eyelids
  • lips
  • lining of the mouth
  • bowel.

Neuromas are painless and do not usually need treatment. They often look like little bumps. They may be pale or the same colour as surrounding tissue. They can make the lips look larger and fuller. Neuromas in the bowel can cause constipation or diarrhoea. Your doctor or specialist nurse can give you information and advice about managing this.

Planning a family

If you have MEN, there is a 1 in 2 (50%) chance that your child could inherit it from you. If you are planning to get pregnant or start a pregnancy, you can talk to your genetics specialist about your options.

Sometimes tests and fertility treatments can be used to ensure a parent’s gene variant is not passed to a child. The Human Fertilisation & Embryology Authority (HFEA) and Genetic Alliance UK have information about this.

Your feelings

You may have many different emotions including anger, resentment, guilt, anxiety and fear. These are all normal reactions. They are part of the process many people go through as they try to come to terms with their condition.

Everyone has their own way of dealing with illness and the different emotions they experience. There is no right or wrong way to cope, but help is there if you need it. You may find it helpful to talk things over with family and friends or your specialist doctor or nurse.

Macmillan is also here to support you. If you would like to talk, you can:

You may also find it helpful to contact AMEND for more information and support.

About our information

  • References

    Below is a sample of the sources used in our family history and cancer information. If you would like more information about the sources we use, please contact us at  cancerinformationteam@macmillan.org.uk

    Monahan KJ, Bradshaw N, Dolwani S, et al. Guidelines for the management of hereditary colorectal cancer from the British Society of Gastroenterology (BSG)/Association of Coloproctology of Great Britain and Ireland (ACPGBI)/United Kingdom Cancer Genetics Group (UKCGG). Gut. 2020; 69: 411–444. Available from DOI: 10.1136/gutjnl-2019-319915 (accessed October 2022).

    NICE. Familial breast cancer: classification, care and managing breast cancer and related risks in people with a family history of breast cancer. Clinical guideline [CG164]. Last updated: 20 November 2019. Available from https://www.nice.org.uk/guidance/CG164 (accessed October 2022).

    NICE. Molecular testing strategies for Lynch syndrome in people with colorectal cancer. Diagnostics guidance [DG27]. Published: 22 February 2017. Available from https://www.nice.org.uk/guidance/dg27 (accessed October 2022).

    NICE. Testing strategies for Lynch syndrome in people with endometrial cancer. Diagnostics guidance [DG42]. Published: 28 October 2020. Available from https://www.nice.org.uk/guidance/dg42 (accessed October 2022).

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Marc Tischkowitz, Reader and Honorary Consultant Physician in Medical Genetics.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

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Date reviewed

Reviewed: 01 October 2022
Next review: 01 October 2025
Trusted Information Creator - Patient Information Forum
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Our cancer information meets the PIF TICK quality mark.

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