Prevention and Diagnosis - Pituitary Cancer

How can I prevent pituitary adenomas?

Given that the only known cause of pituitary adenomas is genetic mutation, there are no specific interventions that would be expected to reduce the risk of pituitary tumor formation.

How are pituitary adenomas diagnosed?

Most pituitary adenomas are discovered because they produce symptoms, either from direct pressure due to their large size (in the case of macroadenomas), or due to the hormones that they secrete. Occasionally, pituitary adenomas are detected when the brain is imaged for an unrelated reason. When a pituitary adenoma is suspected, the physician should perform a thorough history and physical examination. The physical exam should consist of a complete neurologic evaluation and examination for signs of excessive hormone secretion.

A number of blood tests can be performed to look for excess production of hormones. Often, these hormones can be measured directly from a blood sample, although in some cases, additional tests are needed to distinguish if abnormalities on a blood test are due to a pituitary tumor or due to some other cause. Many of these tests are specific to the hormone that is being produced. These tests include a glucose suppression test used to detect pituitary adenomas that produce growth hormone, and a cortisol-stimulation test used to distinguish if abnormal blood cortisol levels are due to a secreting pituitary adenoma or due to a problem in the adrenal glands.
In addition to blood tests, imaging of a suspected pituitary adenoma will be ordered. The most common type of imaging used is Magnetic Resonance Imaging (MRI), which uses magnets to produce a very sharp picture of the inside of the head. Despite the high resolution of MRIs, small microadenomas may not be detectable on an MRI. In those cases, the only way to confirm the diagnosis is by obtaining a biopsy or by resecting the tumor and examining it underneath a microscope.

Less commonly, Computed Tomography (CT or CAT) scans are used. CT scans use x-rays to form a three-dimensional picture of the inside of the body. The ability to detect pituitary tumors on CT scan is significantly worse than on MRI; however, large macroadenomas can sometimes be seen on CT scan.

Ultimately, the only way to confirm a diagnosis of a pituitary adenoma is to examine the tissue underneath a microscope. In most cases of tumors or cancers in other parts of the body, this is done by obtaining a biopsy of the tumor. A biopsy is where a small piece of the suspected tumor is removed (i.e. with a needle, etc.) and examined underneath a microscope. Pituitary adenomas are an exception to this general rule. The accuracy of diagnosing pituitary adenomas through blood tests and radiographic imaging is very good, and often makes a biopsy unnecessary - especially since the pituitary gland is in a difficult area to reach and near a number of critical structures, such as the optic chiasm. Since many pituitary adenomas can be treated without surgery, by using medications or radiation, the issue of accessing this area of the body for biopsy may be irrelevant.

How are pituitary adenomas staged?

There is no official or widely used staging system for pituitary adenomas. In general, pituitary adenomas are classified as either macroadenomas (larger) or microadenomas (smaller), and by whether they are secreting (adenomas that produce hormones, also called functional ) or non-secreting (adenomas that do not produce hormones, also called non-functional ).