Multiple Endocrine Neoplasia Type 1 (MEN1)

Most of these tumors are benign (not cancer).

Most pituitary tumors are benign (not cancer). However, they can cause problems because of the hormones they produce. Or they can grow and press on important structures, such as the brain and nerves of the eyes.

Some neuroendocrine tumors are more likely to be cancerous than others. For example, gastrinomas, glucagonomas, and VIPomas are more often cancer and can spread to other parts of the body and nearby lymph nodes. Insulinomas are almost always benign (not cancer).

These tumors are malignant (cancer), although some tumors behave more aggressively than others. For example, NETs of the thymus tend to grow quickly and be difficult to treat. NETs of the bronchus (part of the lung) tend to grow more slowly.

Most tumors of the adrenal gland are benign (not cancer). In some cases, they can be cancer called adrenocortical carcinoma. Cancer is more likely in larger MEN1-related adrenal tumors.

Meningiomas are tumors that grow on the layers of tissue that cover the brain (meninges). While these tumors most often are not cancerous, they can sometimes cause problems. They might need treatment because of their location near important parts of the brain.

Ependymomas are brain tumors that grow from the ependymal cells that line the fluid filled areas of the brain called the ventricles. They can be low-grade (slow-growing) or high-grade (fast-growing) tumors that might need treatment because of their location near important parts of the brain.

Women with MEN1 have an increased risk of developing breast cancer during their life. Breast cancer in people with MEN1 has been seen at younger ages than expected.

Tumors on the parathyroid glands, located in the neck, are almost always benign (not cancer). But they can cause the glands to be overactive and raise calcium levels in the blood.

Symptoms might include increased thirst, peeing more often, constipation, kidney stones, or low bone density.

In many cases parathyroid tumors do not cause symptoms and are found after blood work done for another reason shows high calcium levels.

Symptoms related to pituitary tumors depend on their size and the type of hormones they make, or if they make hormones at all.

The pituitary is located at the base of the brain near the optic nerves (nerves of the eye). Because of this, symptoms of pituitary tumors can include vision changes, especially peripheral vision (causing tunnel vision), if they grow large enough.

One of the more common pituitary tumors in MEN1 is called a prolactinoma. Prolactinomas make prolactin, a hormone that mainly causes breast milk production. This tumor can cause women to make breast milk, even if they are not pregnant or breastfeeding. It may also interrupt menstrual cycles. In men it can cause sexual dysfunction.

Other types of pituitary tumors can make other hormones. These include growth hormones, reproductive hormones, and stress hormones. Each type of hormone may cause different symptoms or cause no symptoms at all.

In people with MEN1, about 1 in 3 pituitary tumors don’t make any kind of hormones.

Symptoms caused by tumors of the pancreas and gastrointestinal tract depend on whether they make hormones and which hormone they make.

The most common type of MEN1-related tumor of the gastrointestinal tract is called a gastrinoma. It usually starts in the part of the small intestine called the duodenum. These tumors make the hormone gastrin. Too much of this hormone can cause stomach ulcers and diarrhea, a condition called Zollinger-Ellison syndrome.

Other, less common, neuroendocrine tumors can develop in the pancreas, including:

• Insulinomas, which make insulin and can cause low blood sugar levels
• Glucagonomas, which make glucagon and can cause high blood sugar, anemia, and diarrhea
• VIPomas, which make vasoactive intestinal peptide (VIP) and can cause severe diarrhea and low salts in the blood

Previously called carcinoid tumors, these neuroendocrine tumors can sometimes make hormones that cause symptoms like flushing of the face, diarrhea, wheezing, or palpitations. When this happens, it is called carcinoid syndrome.

Most of these tumors do not make hormones, though. These tumors might or might not cause symptoms, depending on their location and size.

Adrenocortical tumors start in the adrenal glands, which sit on top of each kidney. Some adrenocortical tumors can produce hormones that cause the body to make cortisol, a steroid that usually helps the body respond to stress. When too much cortisol is made, it can cause symptoms such as:

• Weight gain
• Stretch marks
• High blood pressure
• High blood sugar levels
• Muscle weakness

Some of these tumors may not cause any symptoms.

If a high level of parathyroid hormone is causing symptoms, it might be treated with surgery to remove most of the parathyroid glands and possibly part of the thymus. If surgery is not an option, it might be treated with medicines to lower calcium levels. If parathyroid tumors do not cause symptoms, no treatment may be needed.

Treatment for pituitary tumors depends on whether they make hormones and their size. These tumors are treated the same as in people without MEN1.

For more information, see Treating Pituitary Tumors.

Treatment for these tumors depends on their size, if they are cancer, and whether they make hormones.

Small tumors that do not make hormones might just be watched. But larger tumors, tumors that are growing quickly, or tumors that make hormones are often removed with surgery.

Tumors that have spread might be treated with chemotherapy, targeted drugs, or other treatments like radiation or ablation, where treatments like heat, cold, or other substances are used to destroy tumors that cause problems.

Other medicines may be used to treat symptoms of extra hormones being made by these types of tumors. For example, medicines that lower stomach acid might be used in the case of a gastrinoma.

For more information, visit Treating Pancreatic Neuroendocrine Tumors or Treating Gastrointestinal Neuroendocrine Tumors.

Often the location, size, and how fast an NET grows is used to decide if a tumor might be watched with imaging or needs treatment right away.

In general, larger NETs and those that are growing quickly are more likely to need treatment. Thymic NETs might grow and spread quickly, so doctors often recommend treatment as soon as they are found. Surgery may be an option if the tumor can be completely removed. Cancer that is left behind may be treated with radiation or chemotherapy.

Smoking increases the risk of developing an NET, especially in the thymus. People with MEN1 should avoid smoking. Some men might be advised to have their thymus removed to reduce the risk of developing a thymus NET. This is especially true for men who smoke.

For more information, visit Treating Lung Neuroendocrine Tumors or Treating Gastrointestinal Neuroendocrine Tumors.

Most adrenocortical tumors in people with MEN1 are not cancer. However, tumors that make hormones, are large, or are suspicious for cancer (growing quickly) are usually removed with surgery.

For more information, see Treating Adrenal Cancer.

Breast cancer and brain tumors in people with MEN1 are treated the same way as in people without MEN1.