Pituitary Tumors

What are pituitary tumors?

Pituitary tumors are abnormal growths of cells in the tissue of the pituitary gland. The pituitary gland is a bean-shaped organ in the center of the brain, just behind and between the eyes. The pituitary gland causes the release of hormones in the body that control growth, metabolism, response to stress, and sexual and reproductive function.¹

Doctors and scientists classify pituitary tumors according to whether or not they spread beyond the pituitary gland:²

• Pituitary adenomas are benign, meaning they are noncancerous and do not spread to other parts of the body. Most pituitary tumors fall into this category. Despite being benign, pituitary adenomas can make the pituitary gland produce too much or too little of certain hormones, causing health problems.
• Pituitary carcinomas are malignant. This means they can spread beyond the pituitary gland into the brain or spinal cord, or into other parts of the body. Very few pituitary tumors are carcinomas.

Because pituitary carcinomas are so rare, this health topic will cover only those pituitary tumors that are adenomas.

• Their size:
  • Microadenomas are smaller than 1 centimeter. Most pituitary adenomas are microadenomas.
  • Macroadenomas are 1 centimeter or larger.
• Whether they secrete hormones²:
  • Functioning pituitary tumors (also called secretory tumors) produce levels of hormones that are too high. Most pituitary tumors are functioning tumors. The symptoms they cause are due to the excessive levels of hormones they produce. These hormones play important roles in the healthy functioning of the body:
    • Prolactin causes a woman's breasts to make milk during and after pregnancy.
    • Adrenocorticotropic hormone (ACTH) is involved in the body's response to stress.
    • Growth hormone helps control body growth and metabolism.
    • Thyroid-stimulating hormone is involved in growth, body temperature, and heart rate.
  • Nonfunctioning pituitary tumors (also called nonsecretory tumors) do not produce hormones. They can press on or damage the pituitary gland and prevent it from secreting adequate levels of hormones.

Symptoms of Functioning Tumors

The symptoms of functioning tumors depend on the particular hormone the tumor is overproducing.¹

The exact cause of pituitary tumors is unknown.

In rare cases, inherited disorders may cause pituitary tumors. These diseases include multiple endocrine neoplasia type 1 (MEN 1) syndrome, Carney complex, and isolated familial acromegaly.¹

For more information about these conditions, read the section Are there disorders associated with pituitary tumors?

It is likely that pituitary tumors are caused by abnormalities in one or more genes, by hormonal abnormalities, or by a combination of these factors.² Scientists, including NICHD researchers, are still working to figure out what causes pituitary tumors.

A doctor will usually begin by giving you a physical exam and asking about your medical history. She or he will check your general health and examine your body for unusual things like lumps.

You might be given tests or procedures such as:¹

• Eye and visual field exam
• Neurological exam: During this exam, the doctor gives you a series of tests and questions to check your coordination, mental status, reflexes, and muscle function.
• Magnetic resonance imaging (MRI) or computed tomography (CT) scan: MRI uses magnetic waves to produce detailed images of the inside of the body, while a CT scan uses X-rays to produce these pictures. These machines create images of the inside of the brain and spinal cord.
• Blood tests to check levels of hormones, blood sugar, and other substances
• Urine tests to determine levels of certain hormones
• Venous sampling: In this type of test, a sample of blood is taken from veins coming from the pituitary gland. Levels of certain hormones are measured in the blood sample.
• Biopsy: Cells or tissues are removed from the pituitary gland. They are then examined under a microscope to check for signs of cancer.

To find out more about diagnosis of pituitary tumors, visit the National Cancer Institute's General Information section on pituitary tumors.

The primary approach for treatment will depend on the type of pituitary tumor.

The most common treatments for pituitary tumors are¹:

• Drug therapy. Drugs can be given to treat the abnormal hormone levels caused by functioning pituitary tumors. The drug given depends on the hormone that is affected by the tumor.
• Surgery. The tumor is removed by performing an operation. The surgeon may reach the pituitary gland through a cut made under the upper lip or at the bottom of the nose between the nostrils. In other cases, the surgeon may cut through the skull to reach the pituitary tumor. Even if the tumor is completely removed, patients are commonly given radiation and chemotherapy after surgery to kill any tumor cells that might be present.
• Radiation therapy. Radiation therapy involves targeting a tumor with high-energy X-rays that kill tumor cells or keep them from growing.
• Chemotherapy. Chemotherapy uses drugs that kill tumor cells or keep them from growing. Chemotherapy can be taken by mouth or injected.

To find out more about treatments for pituitary tumors, visit the National Cancer Institute's Treatment Option Overview section on pituitary tumors.

Most pituitary tumors are curable.¹ If a pituitary tumor is diagnosed early, the outlook for recovery is usually excellent. However, if tumors grow large enough, or grow rapidly, they are more likely to cause problems and will be more difficult to treat.² Lifelong treatment or follow-up is often required, however, to make sure the tumor has not returned.³