Association for
Multiple Endocrine
Neoplasia Disorders

What is MEN1?

There are three main types of tumor that can occur in MEN1. These tumours are usually not malignant or cancer (benign). They occur in the parathyroid glands in the neck, the endocrine pancreas and gut (duodenum) and the pituitary gland under the base of the brain behind the nose.

80% (8 out of 10) of MEN1 patients will have developed at least one of the tumors by the age of 50, and 43% (4 out of 10) by the age of 20. Younger cases have been recorded. The condition varies greatly even within families; not everyone will have the same tumors and they will not occur at the same age. Not all MEN1 patients will have all of the tumors described here.

Blood tests to look at hormone levels and scans of the head, neck and abdominal area are all used to check for tumors. If a tumor is found, surgery may be needed to remove either just the tumor itself or the whole of the affected gland. In some cases treatment with controlling medicines may be used.

Pituitary Tumors

The pituitary gland can be found at the base of the brain behind the nose, in a bony box called the sella turcica . It is very close to the optic nerves from the eyes and therefore, occasionally pituitary tumors can cause problems with vision. They may also cause headaches. 3 out of 10 (30%) of MEN1 patients will develop a pituitary tumor.

There are several different types of benign (non-cancerous) pituitary tumor, which can differ in size (microadenomas of less than 1cm in diameter, or macroadenomas of more than 1cm). All forms of pituitary tumor may be detected using an MRI or CT scan of the head as well as blood tests. Treatment may be in the form of medicine or surgery. This will depend upon the type of tumor and its size. Sometimes small tumors can be treated with tablets or injections although often surgery is needed.

The operation to remove a pituitary tumor is a relatively small one, and although carried out under general anesthetic, it does not involve having to operate on the main part of the head. Pituitary tumors are not brain tumours.

Parathyroid Glands

These small glands lie just next to or are sometimes embedded within the butterfly-shaped thyroid gland in the neck. More than 9 out of 10 (90%) of MEN1 patients will develop a parathyroid tumor called an adenoma. These tumors release large amounts of parathyroid hormone (PTH) and so can be easily found using blood and urine tests.

Some symptoms of an untreated parathyroid tumors include irritability, ulcers, kidney stones, pancreatitis, bone fractures, osteoporosis, tiredness, muscle or bone pain, indigestion, poor memory and constipation. However most patients will have very few of these symptoms particularly when diagnosed and treated early on. At the moment, the recommended treatment for parathyroid tumors is a relatively small operation to remove all of the glands, and involves only a few days in hospital. Medicines are available to control parathyroid growth where surgery is not possible.  After parathyroid glands are removed, patients may have to take a Vitamin D capsule to help the body absorb calcium.

Pancreatic Neuroendocrine Tumors

The pancreas lies in the abdomen behind the stomach and is connected to a part of the small intestines called the duodenum. It produces several hormones important for the body’s energy levels. 3 out of 4 (75%) of MEN1 patients will develop one of several pancreatic neuroendocrine tumors and 1 in 10 (10%) of those will develop more than one type of tumor. While most of the tumors will produce large amounts of hormones, some may not be active (non-functioning). Up to half of the tumors may become malignant (cancerous) if left untreated. Most pancreatic tumors are found using an MRI scan and blood tests. If the growths are very small, other types of scan may be used.

Treatment depends on the size and type of tumor. Anti-ulcer medications can be used to control symptoms of tumors called Gastrinomas, but other types of tumor are usually treated with surgery. The operation may remove just the tumor, or remove the whole or a part of the pancreas. If the whole or a major part of the pancreas is removed, a patient will then have diabetes, which must be treated with regular insulin injections. Please note that the neuroendocrine pancreatic tumours of MEN1 are NOT the same as the more common pancreatic cancer, adenocarcinoma.

Author: Jo Grey, AMEND CEO, with the help of the AMEND Medical Advisory Team

For further detailed information on MEN1, read AMEND USA’s MEN1 Patient Information Book (we recommend that you discuss the contents of this book with your specialist – it is not for use in self-diagnosis, and not all of the information it contains may be relevant to you).

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