What is multiple endocrine neoplasia type 1?

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary condition associated with tumors of the endocrine (hormone producing) glands. MEN1 was originally known as Wermer syndrome. The majority of tumors in people with MEN1 are benign (noncancerous) and the cancer risk is low. The most common tumors seen in MEN1 involve the parathyroid gland, pancreas, and pituitary gland. Other endocrine tumors seen in MEN1 include adrenalcortical and carcinoid tumors, as well as tumors in other parts of the digestive tract. Non-endocrine tumors are also seen in MEN1. These tumors can include:

• Facial angiofibromas (tumors of blood vessels and fibrous tissue)
  
  
• Collagenomas (flesh-colored tumors on the skin)
  
  
• Lipomas (fatty tumors)
  
  
• Meningiomas (tumors from nervous system tissue)
  
  
• Ependymomas (tumors from nervous system tissue)
  
  
• Leiomyomas (smooth muscle tumors)

Although most of the tumors associated with MEN1 are benign, the tumors may cause medical problems due to their location or increased hormone production.

What causes MEN1?

MEN1 is a genetic condition. This means that the cancer risk and other features of MEN1 can be passed from generation to generation in a family. The gene associated with MEN1 is also called MEN1. A mutation (alteration) in the MEN1 gene gives a person an increased risk of developing endocrine tumors and other symptoms of MEN1. Research is ongoing to learn more about MEN1.

How is MEN1 inherited?

Normally, every cell has two copies of each gene: one inherited from the mother and one inherited from the father. MEN1 follows an autosomal dominant inheritance pattern, in which a mutation happens in only one copy of the gene. This means that a parent with a gene mutation may pass along a copy of their normal gene or a copy of the gene with the mutation. Therefore, a child who has a parent with a mutation has a 50% chance of inheriting that mutation. A brother, sister, or parent of a person who has a mutation also has a 50% chance of having the same mutation.

How common is MEN1?

It is estimated that about one in 30,000 people has MEN1. About 10% of people with MEN1 do not have a family history of the condition. They have a de novo (new) mutation in the MEN1 gene.

How is MEN1 diagnosed?

MEN1 is suspected when a person has at least two of the most common tumors listed.

• Parathyroid
  
  
• Pancreatic
  
  
• Pituitary

If a person has a family history of MEN1, they are suspected of also having MEN1 if they have a parathyroid, pancreatic, or pituitary tumor. Genetic testing for mutations in the MEN1 gene is available for people suspected to have MEN1. A mutation in the MEN1 gene is found in about 80% to 90% of families diagnosed with MEN1. Approximately 65% of people with symptoms of MEN1, but no family history, will have a mutation in the MEN1 gene.

What are the estimated cancer risks associated with MEN1?

Nearly all tumor types have the potential to become cancerous. However, the overall cancer risk in people with MEN1 is estimated to be less than 10%.

What are the screening options for MEN1?

Current suggested screening for people who are known or suspected to have MEN1 includes:

• Yearly blood tests for serum prolactin and insulin-like growth factor 1 (IGF-1) level and yearly fasting glucose, insulin, and proinsulin levels, beginning at age 5
  
  
• Yearly blood tests for parathyroid hormone (PTH) and ionized calcium, beginning at age 8
  
  
• Yearly blood tests for fasting gastrin level and fasting and meal stimulated pancreatic polypeptide, fasting vasoactive intestinal peptide (VIP), and glucagons, beginning at age 20
  
  
• Magnetic resonance imaging (MRI) or computerized tomography (CT or CAT) scan of the brain, every three years beginning at age 5
  
  
• MRI or CT of the chest and abdomen, every two to three years, beginning at age 20

Screening guidelines may change over time as new technologies are developed and more is learned about MEN1. It is important to talk with your doctor about appropriate screening tests.

Questions to ask the doctor

If you are concerned about your risk of cancer, talk with your doctor. Consider asking the following questions of your doctor:

• What is my risk of developing cancer?
  
  
• What can I do to reduce my risk of cancer?
  
  
• What are my options for cancer screening?

If you are concerned about your family history and think you or other family members may have MEN1, consider asking the following questions:

• Does my family history increase my risk of developing cancer?
  
  
• Should I meet with a genetic counselor?
  
  
• Should I consider genetic testing?

Additional resources

What to Expect When You Meet With a Genetic Counselor

National Cancer Institute (NCI)
www.nci.nih.gov

American Cancer Society
www.cancer.org

CancerCare
www.cancercare.org

To find a genetic counselor in your area, ask your doctor or visit these websites:

National Society of Genetic Counselors
www.nsgc.org

National Cancer Institute
www.cancer.gov/search/geneticsservices