Testosterone

Definition

Synthetic derivatives of the natural hormone testosterone are used to reduce the size of hormone-responsive tumors.

Purpose

Testosterone-related drugs are used to treat advanced disseminated breast cancer in women.

Description

Testosterone belongs to a class of hormones called androgens. These are male hormones responsible for the development of the male reproductive system and secondary male sexual characteristics such as voice depth and facial hair. Testosterone is normally produced by the testes in large quantities in men. It also occurs normally in smaller quantities in women.

Several man-made derivatives of testosterone are used to treat advanced disseminated breast cancer in women, especially when cancer has spread to the bones. The most common of these testosterone-like drugs are fluoxymesterone (Halotestin) and methyltestosterone (Testred). These androgens are used only in women who have late-stage breast cancer and who meet specific criteria. These criteria include:

• The patient is postmenopausal.
• The tumors have been shown to be hormone-dependent.
• The tumors have spread, often to the bone, or recurred after other hormonal cancer treatments.

Using testosterone derivatives to treat breast cancer is a palliative treatment. This means that the treatment helps relieve symptoms but does not cure the cancer. These drugs are approved by the United States Food and Drug Administration (FDA), and their cost is usually covered by insurance.

Clinical trials are currently underway that involve the use of testosterone-related androgens in varying combinations with other drugs to treat advanced cancers. The selection of clinical trials changes constantly. Current information on the availability and location of clinical trials can be found at the following web sites:

• National Cancer Institute. (800) 4-CANCER or <http://cancertrials.nci.nih.gov>.
• National Institutes of Health Clinical Trials. <http://clinicaltrials.gov>.
• Center Watch: A Clinical Trials Listing. <http://www.centerwatch.com>.

Recommended dosage

Dosage is individualized and depends on the patient's body weight and general health, as well as the other drugs she is taking and the way her cancer responds to hormones. Halotestin comes in tablets of 2 mg, 5 mg, or 10 mg. A standard dose of Halotestin for inoperable breast cancer is 10 to 40 mg in divided doses daily for several months. Tablets should be stored at room temperature. Testred comes in 10 mg capsules. A standard dose for women with advanced breast cancer is 50 to 200 mg daily.

Precautions

Women who take testosterone derivatives for advanced breast cancer are postmenopausal, so the usual precautions about avoiding pregnancy when receiving androgen therapy do not apply.

Side effects

The most serious side effect of these drugs is hypercalcemia, a condition in which too much calcium circulates in the blood. This occurs because these drugs liberate calcium from bones. Calcium levels are monitored regularly, and the drug is discontinued if hypercalcemia occurs. Another serious (but less common) side effect is the development of tumors in the liver. Other side effects include deepening of the voice, development of facial hair and acne, fluid retention, and nausea.

Interactions

As with any course of treatment, patients should alert their physician to any prescription, over-the-counter, or herbal remedies they are taking in order to avoid harmful drug interactions. Patients should also mention if they are on a special diet, such as low salt or high protein. They should not take calcium supplements, since testosterone already has the potential to increase circulating calcium to dangerous levels.

Testosterone derivatives may interact with anticoagulant drugs (blood thinners) such as Coumadin.

Tish Davidson, A.M.

Hormone

—A chemical produced by a gland in one part of the body that travels through the circulatory system and affects only specific receptive tissues at another location in the body.

Postmenopausal

—Women have stopped menstruating, usually because of their age.

Testes

—Egg-shaped male sexual organs contained in the scrotum that produce testosterone and sperm.