|
Introduction
Many breast tumors are "estrogen sensitive," meaning that the hormone estrogen makes them grow. Aromatase inhibitors (AIs) help to prevent the growth of these tumors by lowering the amount of estrogen in the body.
Estrogen is produced by the
ovaries
and other
tissues
of the body, using a substance called aromatase. AIs do not block estrogen production by the ovaries,
but they can block other tissues from making this hormone.
That's why AIs are used mostly in women who have reached
menopause,
when the ovaries are no longer producing estrogen.
Another drug, tamoxifen, also helps to prevent the growth of estrogen-sensitive breast tumors, but it works differently from AIs. Whereas AIs reduce the amount of estrogen in the body, tamoxifen blocks a tumor's ability to use estrogen.
Currently, three AIs are approved by the U.S. Food and Drug Administration: anastrazole (Arimidex®), exemestane (Aromasin®), and letrozole (Femara®).
Recently, a study of breast cancer survivors found that women who took letrozole after completing five years of therapy with tamoxifen were significantly less likely to have their cancer return than women who did not take letrozole
(see Letrozole Helps Breast Cancer Survivors).
Another study found that women who took tamoxifen for two or three years after surgery to remove
breast cancer and then switched to the drug exemestane had fewer
recurrences
of breast cancer than women who stayed on tamoxifen for five years following surgery
(see Exemestane Following Tamoxifen Reduces Breast Cancer Recurrences).
Next Section > |
