What is Anastrozole?

Anastrozole is a medication used as hormonal therapy for the treatment of certain types of breast cancer in post-menopausal women. This therapy works by suppressing the activity of estrogen in the body and thus inhibiting the growth of breast cancer cells that are dependent on estrogen. Where available, this medication is sold under the brand names Arimidex® and AstraZeneca®.

Hormone therapy medications are synthetic hormones or hormone inhibitors that either mimic or suppress hormone activity in the body. For example, women who are going through menopause can opt for hormone replacement therapy. Symptoms of menopause are caused by lack of estrogen, so the hormone replacement therapy provides additional estrogen to relieve symptoms.

Anastrozole hormone therapy for breast cancer treatment works in a similar fashion in that it moderates the effects of estrogen in the body. This treatment, however, has a significantly different effect on estrogen. This hormone therapy actually reduces the amount of estrogen available for use in the body, rather than mimicking its effects to provide the body with an additional supply.

Breast cancer anastrozole therapy works because many types of breast cancer are dependent on estrogen, and cannot continue to grow without it. In women who have been through menopause, the main source of the body’s estrogen is through the conversion of hormones called androgens. These hormones are converted into estrogen by an enzyme called aromatase.

Anastrozole is an aromatase inhibitor, which means it blocks the activity of the aromatase enzyme and reduces the amount of estrogen that is produced. This in turn reduces the supply of estrogen available to breast cancer cells, and it can slow the growth of the cancer and even cause tumors to shrink. With this hormone therapy, the best results are achieved in post-menopausal women who have early-stage estrogen-dependent breast cancer. Late-stage cancer sometimes is less responsive to this type of hormone therapy.

This type of hormone therapy has many potential side effects. The most common side effects are not harmful but can be unpleasant or painful. Possible side effects include hot flashes, vaginal dryness or bleeding, nausea, vomiting, diarrhea, headaches, thinning hair, skin rashes, joint pain, muscle stiffness and lethargy. Potentially serious side effects include sudden body weakness or numbness, swollen glands and sudden confusion, vision problems, speech problems or balance problems. All side effects should be reported to a doctor to determine whether further attention is needed.

Hormone therapy is not the only use of this aromatase inhibitor. Aromatase inhibitors sometimes are used as bodybuilding supplements by people who are trying to increase muscle mass, because this type of hormone therapy can reduce the side effects of anabolic steroid use. It should be noted that anastrozole and similar aromatase inhibitor supplements are not steroids and are neither illegal nor banned by major sporting bodies, like anabolic steroids themselves are in many countries.