NCCN Guidelines for Patients
Stage IV Breast Cancer, Version 1.2014
Aromatase inhibitors are drugs that lower estrogen
levels in the body. These drugs work by blocking a
protein that makes estrogen. However, they can’t stop
the ovaries of premenopausal women from making
estrogen. For this reason, these drugs are only used
among postmenopausal women. Three drugs in this
category are anastrozole, letrozole, and exemestane.
In very special circumstances, exemestane is given
with everolimus. Read
on page 22
for more information.
Although not used often, some doctors prescribe
high doses of hormones to treat breast cancer.
Such hormones include megestrol acetate,
fluoxymesterone, and ethinyl estradiol. It is not known
how high doses of hormones stop breast cancer cells
with hormone receptors from growing.
The ovaries are the main source of estrogen and
progesterone in premenopausal women. Removing
them stops most of the hormones from being made.
Surgery that removes both ovaries is called a bilateral
oophorectomy. Radiation therapy to the ovaries
also stops the ovaries from making estrogen and
progesterone, but isn’t often used. Both treatments
are forms of ovarian ablation.
Ovarian suppression is when drugs are used to
tell the ovaries to make less estrogen. Ovarian
suppression is achieved with drugs called LHRH
LHRH is a hormone made in the brain that helps to
regulate estrogen production in the ovaries. LHRH
agonists stop LHRH from being made, which stops
the ovaries from making more estrogen. Goserelin
acetate and leuprolide are LHRH agonists and should
be given as monthly injections under the skin.