Drug Therapy

Medications have become available for selected types of tumors. These drugs may be quite effective in some circumstances:

Dopamine agonists are effective in lowering prolactin levels and may even shrink the size of a prolactin-secreting tumor.

Dostinex, a long-acting dopamine agonist. Dostinex (cabergoline tablets) joins bromocriptine as a drug product indicated to treat hyperprolactinemia, however, Dostinex is more convenient for patients (two doses per week for Dostinex versus one to three doses each day for bromocriptine). Dostinex is an effective and generally well tolerated.

Bromocriptine “Parlodel” is a dopamine agonists. Long-term treatment may be necessary. With treatment, regular menses are usually restored and galactorrhea stopped. Successful pregnancies have been accomplished with the delivery of healthy children. However, these agents do tend to produce frequent side effects such as nausea, weakness, and dizziness.

Pergolide Mesylate (Permax) A ergoline derivative, pergolide mesylate, effectively inhibits PRL secretion and is an option for the medical treatment of prolactinomas. This dopamine agonist is approximately 100 times more potent than BC and suppresses PRL secretion for up to 24 h after a single dose, allowing effective control of hyperprolactinemia with once daily dosing. Pergolide is approved in the United States only for the therapy of Parkinson’s disease, where it has been used safely at doses more than 10 times those used for PRL-secreting tumors.

Octreotide. This injectable medication is particularly useful in lowering growth hormone secretion. It is important to remember that drug therapy may only control the secretion of some tumors and not actually decrease the size of the tumor. The persistence of these tumors may necessitate long-term administration of the drug.

Somavert is the first in a new class of medicines called growth hormone receptor antagonists and the only medicine designed to specifically block the effects of excess growth hormone in acromegaly.

Somavert (pegvisomant), an analog of human growth hormone, is an injectable medication that has been structurally altered to act as a growth hormone (GH) receptor antagonist. Over production of growth hormone leads to abnormally high insulin-like growth factors (IGF-I), which then cause acromegaly like symptoms.

Somavert is indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery and/or radiation therapy and/or other medical therapies, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum IGF-I levels.

Somavert is available in single-dose, sterile glass vials in 10, 15, or 20 mg strengths.

Approval Status: Approved March 2003

Cushing’s

Cortisol-reducing drugs. Although there is no medication to control Cushing's disease, a few drugs have been used with varying success. These agents, such as ketoconazole, metyrapone, and mitotane, work to lower the secretion of the adrenal steroids.

Diagnosis of Pituitary Adenomas

The symptoms of a pituitary adenoma vary with the hormone(s) being secreted. These symptoms can range from the absence of menstruation (amenorrhea) or inappropriate lactation (galactorrhea) often seen in women with prolactin-secreting tumors to the enlargement of the hands, feet, and jaw associated with growth hormone-secreting tumors. The table below outlines the various symptoms by tumor type. There are also more general symptoms, including headaches, visual disturbances, and nausea, that can be caused by any type of pituitary tumor. These symptoms often occur if the tumor becomes large enough to compress neighboring structures, including the brain and optic nerves.
If any of these symptoms are present in an individual, several tests may be done to confirm the diagnosis of a pituitary adenoma. Blood tests are generally performed to determine hormone levels. Blood tests can also determine whether any hormone excess is the result of pituitary dysfunction.

In addition, a magnetic resonance imaging (MRI) scan can reveal whether or not the pituitary gland is enlarged. The results of each test are examined by an endocrinologist in order to confirm the diagnosis of a pituitary adenoma and to form a treatment plan.

Treatment of Pituitary Adenomas

The treatment plan will be specific for each tumor type, as well as for each patient, and may include surgery, radiation, and/or drug therapy. The most common methods of treatment for the most prevalent tumor types are outlined in the table below. Treatment may include only one or a combination of these methods.

STANDARD TREATMENT OPTIONS

Observation
Based on the known slow growth of most pituitary tumors, the physician may recommend observation only for the patient who does not have any evidence of a hormonal syndrome and as long as the tumor does not compress the optic chiasm or nerves. This is more likely to be the case for older patients. Tumors in younger patients have a longer time to grow and therefore other forms of treatment may be recommended.

Observation as a management recommendation means that the patient is followed closely and the tumor is reimaged by MRI at reasonable intervals. In general, MRI scans are performed more frequently during the first year after diagnosis. Once the stability of the tumor has been established, MRI scans may be taken less frequently. With observation, the patient is followed in this fashion until any tumor growth is noted on the MRI scans. If growth should occur, then appropriate treatment is recommended at that time.