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Multiple endocrine neoplasia 1 (MEN1) is a rare condition where tumours develop in the endocrine system.
We hope this information answers your questions. If you have any further questions, you can ask your doctor or nurse at the hospital where you are having your treatment.
MEN stands for multiple endocrine neoplasia. MEN is a rare condition caused by a faulty gene|, which can be passed on within families from one generation to another (inherited).
In multiple endocrine neoplasia, a number of different tumours develop in the endocrine system. The word neoplasia means 'new growth' or 'tumour'.
There are two types: MEN1 and MEN2|. Because they have similar names, MEN1 and MEN2 are often confused. In fact, they are completely separate conditions with different genetic causes. MEN1 can't turn into MEN2 and MEN2 can't turn into MEN1.
MEN1 tumours can be non-cancerous (benign) or cancerous (malignant). Malignant tumours can spread to other parts of the body, but benign tumours do not spread.
MEN1 is diagnosed when a person has more than two endocrine tumours in the body, and is found to have a faulty gene (genetic mutation). A person can also be diagnosed as having MEN1 if they have one endocrine tumour and one or more members of their family have been diagnosed with MEN1.
The endocrine system is a network of endocrine glands and nerves throughout the body. Endocrine glands produce and release hormones that circulate around the body in the blood.
Hormones keep an even balance of chemicals and fluid within the body, and help us respond to changes in the environment. Normally, the hormones released by endocrine glands are carefully balanced to meet the body's needs.
The endocrine glands include the pituitary gland (which lies directly underneath the brain), the thyroid gland (in the front of the neck), the parathyroid glands (just behind the thyroid gland), and the adrenal glands (on top of the kidneys in the abdomen).
MEN1 is a very rare condition that can affect men or women at any age. Although it tends to be an inherited condition, known as familial MEN1, it can sometimes occur in people who don't have any family members diagnosed with it – known as sporadic MEN1.
If a person has MEN1, they are known as a MEN1 carrier. There is a 1 in 2 (50%) chance that they will pass the genetic mutation on to their children.
MEN1 occurs because of an inherited genetic change (mutation). We all inherit our genes from our parents. Genes affect the way our bodies grow, work and look.
In people with MEN1, there is a mutation, or mistake, in one gene of every cell. This mutation causes tumours to develop in the endocrine system. It isn't known exactly what causes this genetic change – research is ongoing to try to find this out.
Almost all people with MEN1 will develop overactivity of the parathyroid glands, known as hyperparathyroidism, at some stage in their life. This is often shown by an abnormally high level of calcium in the blood (hypercalcaemia). There may be tumours in the parathyroid glands, which are usually benign.
Tumours can also develop in the digestive system (gastrointestinal tract or GI tract), usually in the stomach, intestines and/or pancreas. These tumours can be benign or malignant.
Other tumours can develop in the pituitary gland| or the adrenal glands|, which are usually benign.
Rarely, people may develop a particular type of tumour (known as a carcinoid tumour|) in the chest, thymus gland (behind the breastbone) or the gastrointestinal tract.
The symptoms for people with MEN1 can vary according to whether or not tumours develop and where these tumours are. Symptoms often occur because a tumour is causing too many hormones to be produced. The particular symptoms depend on:
The main endocrine tumours, and some of the most common symptoms they cause, are listed below. It's important to remember that these tumours can affect people in different ways, and that the symptoms can be similar to those caused by many other non-cancerous conditions.
Symptoms of parathyroid gland tumours| may be:
Symptoms of pituitary gland tumours can include headaches and sight problems. Infertility| may also occur.
Some people have a condition called acromegaly, which affects growth leading to an enlargement of the hands and feet. Acromedgaly can also lead to high blood pressure and diabetes.
Women may notice that their periods stop and they may produce small amounts of breast milk. Men might be unable to have an erection (impotence).
There are several different types of GEP tumours|. They tend to develop in the organs of the digestive system such as the stomach (gastro), intestines (entero) and the pancreas. Below are the possible symptoms of different types of GEP.
Symptoms can include:
Adrenal gland tumours| tend to be 'non-functioning', which means there is no excess production of hormones and there are no obvious symptoms.
MEN1 is due to an alteration (mutation) in a gene. We all have many thousands of genes. We have two copies of every gene, one inherited from our mother and the other inherited from our father.
People with MEN1 have one normal MEN1 gene and one MEN1 gene with an alteration (mutation). They can pass on either copy to their children, so there is a one in two (50%) chance that a child of someone with MEN1 will inherit the condition. This chance is the same for each child, regardless of their sex.
It's possible to identify the gene change in an affected person by doing a genetic test|. This involves analysing the DNA (genetic code) from a blood sample. This can be a time-consuming process, which often takes a number of months.
In some cases, the gene change can't be found even though the person is affected by MEN1. This is likely to be due to technical limitations of the test.
Before genetic testing is carried out, counselling is arranged to help people to understand how the test results may affect them individually and as a family.
If a gene change is found, other family members can then be tested to see if they have inherited the same gene change. If they haven't, then they don't need any monitoring. However, if other relatives have inherited it, they will need to be closely monitored to detect any possible complications at an early stage.
Your doctor will discuss with you how you will be monitored.
The treatment for MEN1 depends on which tumours have developed. It can involve surgery| to remove the tumours or medicines to help control the symptoms.
Unfortunately, there is no way of changing the genetic mutation. However, problems caused by MEN1 can often be recognised at an early stage and successfully treated or controlled.
Careful monitoring enables your doctor to adjust your treatment as needed, and to check for any new problems that MEN1 may cause.
Research into treatment for MEN1 is ongoing and advances are being made. Doctors use clinical trials| to assess new treatments. Before any trial is allowed to take place, an ethics committee must have approved it and agreed that the trial is in the interest of the patients.
You may be asked to take part in a clinical trial. Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from a trial at any stage. You will still receive the best standard treatment available.
The need for practical and emotional support is different for each person. Some people with MEN1 may find that their life is largely unaffected, but for others the condition may be a source of great fear and distress.
You may have many different emotions| including anger, resentment, guilt, anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their condition.
Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. You may wish to contact our cancer support specialists| for information about counselling in your area.
AMEND| is a service for patients, families and friends affected by MEN disorders.
This information has been compiled using information from a number of reliable sources, including:
Thanks to Professor John Monson, Professor of Clinical Endocrinology, and the people affected by cancer who reviewed this edition. Reviewing information is just one of the ways you could help when you join our Cancer Voices network|.
Content last reviewed: 1 January 2013
Next planned review: 2015
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
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© Macmillan Cancer Support 2013
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