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Hormone therapy is another form of systemic therapy. Like
chemotherapy, hormone therapy can be used either as an adjuvant therapy
to help reduce the risk of cancer recurrence after surgery or when the
cancer has become metastatic.
Some breast cancers grow in response to the hormone estrogen.
Estrogen is usually thought of as a "female" hormone, but men have it
in their bodies as well, just at lower levels. About 9 out of 10 breast
cancers in men have hormone receptors on the surface of their cells --
that is, their cancers are estrogen receptor (ER)-positive and/or
progesterone receptor (PR)-positive. This makes them more likely to
respond to hormone treatments. Hormone therapy does not help patients
whose tumors are both ER- and PR-negative.
Several approaches to blocking the effects of estrogen or
lowering estrogen levels are used to treat breast cancer in women.
While many of these may work in men as well, doctors have the most
experience with using anti-estrogen drugs such as tamoxifen in men.
In the metastatic setting, hormonal treatments are often used
in a sequence. For example, tamoxifen may be tried first. If the cancer
does not respond or if it grows back after an initial response, other
hormonal treatments may be tried.
Tamoxifen: Tamoxifen
works by blocking the estrogen receptors on cancer cells, which
prevents estrogen from spurring their growth. It is taken daily in pill
form, usually for 5 years, to reduce the chances of the cancer coming
back after surgery. Tamoxifen can also be used to treat advanced breast
cancer.
The most common side effects include fatigue, hot flashes, and
sexual problems. A rare but more serious side effect is blood clots,
which usually form in deep veins of the leg. In some cases, this
increased risk of clotting may lead to a heart attack, stroke, or blood
clots spreading to the lungs (pulmonary embolism). Call your doctor or
nurse right away if you develop pain, redness, or swelling in your
lower leg (calf), shortness of breath, chest pain, sudden severe
headache, confusion, or trouble speaking or moving.
Aromatase
inhibitors: This group of drugs includes anastrozole
(Arimidex), letrozole (Femara), and exemestane (Aromasin). They block
the production of small amounts of estrogen by the adrenal glands. They
are taken daily as pills. They have been found to be very effective in
treating breast cancer in women, but they have not been well studied in
men. Still, some doctors use them as the first line of hormone therapy
instead of tamoxifen. Clinical trials are also under way to look at
using aromatase inhibitors along with LHRH analogs (see below).
The main side effects of these drugs are thinning of the bones
and joint stiffness.
Megestrol:
Megestrol (Megace) is a progesterone-like drug. It is unclear how it
stops cancer cells from growing, but it appears to compete for hormone
receptor sites in the cells. This is an older drug that is usually
reserved for men who are no longer responding to other forms of hormone
therapy. Megestrol may increase the risk for blood clots and frequently
causes weight gain through an increase in appetite.
Orchiectomy
(castration): Surgical removal of the testicles greatly
lowers the levels of testosterone and other androgens (male hormones)
in the body. Most male breast cancers contain androgen receptors that
may cause the cells to grow. Androgens can also be converted into
estrogens in the body. Orchiectomy shrinks most male breast cancers,
and may help other treatments like tamoxifen become more likely to
work. This treatment was once quite common, but it is now used less
often because of new non-surgical approaches to lowering androgen
levels, such as those below.
Luteinizing
hormone-releasing hormone (LHRH) analogs and anti-androgens:
LHRH analogs such as leuprolide (Lupron) and goserelin (Zoladex) affect
the pituitary gland and, indirectly, cause the testicles to lower their
production of androgens. They are given as shots either monthly or
every few months. Anti-androgens such as flutamide and bicalutamide
work by blocking the effect of male hormones on breast cancer cells.
These drugs are taken as daily pills. LHRH analogs, either alone or
with anti-androgens, are often effective in shrinking male breast
cancers. Doctors are also studying the use of LHRH analogs along with
aromatase inhibitors.
Possible side effects of hormone therapy
While some of these drugs have unique side effects (see
descriptions above), in general they can cause loss of sexual desire,
trouble having an erection, weight gain, hot flashes, and mood swings.
Be sure to discuss any such side effects with your cancer care team
because there may be ways to treat them.
Last Medical Review: 09/24/2008 Last Revised: 05/13/2009
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