Cancer treatment for certain
hormone-sensitive cancers
The term "hormone
therapy" might make you think of women taking estrogen to reduce their
symptoms of menopause or men taking testosterone to slow the effects of aging.
But hormone therapy for cancer — also called endocrine therapy — is something
completely different. Hormone therapy for cancer alters the hormones in your
body to help control or cure cancer.
Hormone therapies associated
with menopause and aging seek to increase the amount of certain hormones in
your body to compensate for age- or disease-related hormonal declines. But
hormone therapy as a cancer treatment either reduces the level of specific
hormones in your body or alters your cancer's ability to use these hormones to
grow and spread.
If your cancer is one that is
sensitive to hormones, you might benefit from hormone therapy as part of your
cancer treatment. Learn the basics of hormone therapy, how it works as a cancer
treatment and its side effects. That way you'll be prepared to discuss it if
your doctor recommends it as a cancer treatment option.
How hormone therapy cancer
treatment works
Specific types of tumors — most
commonly tumors of the breast and of the prostate — rely on hormones such as
estrogen and testosterone to survive and grow. Hormone therapy is a cancer
treatment that attacks these hormone-dependent tumors in two ways:
By altering your cancer's
hormone supply, hormone therapy can make your tumors shrink. But this cancer
treatment only works for hormone-sensitive cancers.
Who can benefit from hormone
therapy cancer treatment
If your cancer is hormone
sensitive, you might benefit from hormone therapy as part of your cancer
treatment. Your doctor can tell you whether or not your cancer is sensitive to
hormones. This is usually determined by taking a sample of your tumor (biopsy)
for analysis in a laboratory.
Cancers that are most likely to
be hormone-receptive include:
Not every cancer of these types
is hormone-sensitive, however. That's why the cells of your cancer must be
analyzed to determine if hormone therapy is appropriate for you.
Uses for hormone therapy
cancer treatment
Hormone therapy is rarely used
as a main (primary) cancer treatment. It's usually used in combination with
other types of cancer treatments, including surgery, radiation and
chemotherapy.
Your doctor might use a hormone
therapy before you begin a primary cancer treatment, such as before surgery to
remove a tumor. This is called neoadjuvant therapy.
Hormone therapy can sometimes shrink a tumor to a more manageable size so that
it's easier to remove during surgery.
Hormone therapy is sometimes
given in addition to the primary treatment — usually after — in an effort to
prevent the cancer from recurring (adjuvant therapy). If you've had surgery to
remove your tumor and it appears that all of your cancer has been removed, your
doctor might use hormone therapy to try to keep your cancer from coming back.
In some cases of advanced (metastatic) cancers, such as in advanced prostate cancer
and advanced breast cancer, hormone therapy is sometimes used as a the main
treatment.
Researchers are also exploring
the use of hormone therapies to prevent cancer from occurring in people with a
high risk of cancer.
Types of hormone therapy
Hormone therapy can be given in
several forms, including:
Surgery
Surgery can reduce the levels of hormones in your body by removing the parts of
your body that produce the hormones, including:
Because certain drugs can
duplicate the hormone-suppressive effects of surgery in many situations, drugs
are used more often than surgery for hormone therapy. And because removal of
the testicles or ovaries will limit an individual's options when it comes to
having children, younger people are more likely to choose drugs over surgery.
Radiation
Radiation is used to suppress the production of hormones. Just as is true of
surgery, it's used most commonly to stop hormone production in the testicles,
ovaries, and adrenal and pituitary glands. Your doctor might recommend
radiation therapy rather than surgery if surgery is too risky for you or if it
carries too many side effects.
Drugs
Various drugs can alter your body's production of
estrogen and testosterone. These can be taken in pill form or by means of
injection. The most common types of drugs for hormone-receptive cancers
include:
Anti-hormones
Anti-hormones block your cancer cells' ability to interact with the hormones
that propel your cancer's growth. Though these drugs don't
reduce your body's production of hormones, anti-hormones block your cancer's
ability to use these hormones. Anti-hormones include the anti-estrogens tamoxifen (Nolvadex) and toremifene (Fareston) for breast
cancer, and the anti-androgens flutamide (Eulexin) and bicalutamide (Casodex) for prostate cancer.
Aromatase inhibitors
Aromatase inhibitors (AIs)
target enzymes that produce estrogen in postmenopausal women, thus reducing the
amount of estrogen available to fuel tumors. AIs are
only used in postmenopausal women because the drugs can't prevent the production
of estrogen in women who haven't yet been through menopause. Approved AIs include letrozole (Femara), anastrozole (Arimidex) and exemestane
(Aromasin). It has yet to be determined if AIs are
helpful for men with cancer.
Luteinizing hormone-releasing hormone (LH-RH)
agonists and antagonists
LH-RH agonists — sometimes called analogs — and LH-RH antagonists reduce the
level of hormones in your body by altering the mechanisms in your brain that
tell your body to produce hormones.
LH-RH agonists are essentially a
chemical alternative to surgery for removal of the ovaries for women, or of the
testicles for men. Depending on your cancer type, you might choose this route
if you hope to have children in the future and want to avoid surgical
castration. In most cases the effects of these drugs are reversible.
Examples of LH-RH agonists
include:
One LH-RH antagonist is
currently approved for men with prostate cancer — abarelix
(Plenaxis) — and is also under investigation for use
in women with breast cancer.
Side effects of hormone
therapy
Most of the side effects of
hormone therapy are temporary. However, surgery and radiation can cause
permanent damage to your ovaries or testicles.
Common side effects in men
undergoing hormone therapy include:
In women undergoing hormone
therapy, side effects can include symptoms similar to those of menopause, such
as:
Resistance to hormone
therapy
If you opt for hormone therapy as
a cancer treatment, be aware that the effects of hormone therapy may be
limited. Most advanced hormone-sensitive cancers eventually become resistant to
hormone treatment and find ways to thrive without hormones.
For instance, many women who've
had surgery for breast cancer take tamoxifen only for
five years because taking it for a longer period doesn't offer any further
benefit and may actually increase the risk that cancer will recur. But you're
not out of options at the end of those five years. Your doctor may prescribe
another form of hormone therapy to which your cancer may respond. Women who've
taken tamoxifen may be able to take an aromatase inhibitor, such as letrozole.
If you have prostate cancer,
your doctor might prescribe intermittent dosing of hormone therapy drugs in an
attempt to prevent your cancer from becoming resistant to therapy. This means
you won't take a drug continuously for several years. Instead you'll start and
stop taking the drug as your doctor closely monitors your cancer.
Other hormone treatments for
cancer
Certain cancers produce
excessive levels of hormones. Though rare, cancers such as carcinoid
tumors, pheochromocytomas and other neuroendocrine cancers lead to production of these higher
levels of your body's natural hormones. The excess hormones can cause such
signs and symptoms as sweating, flushing, high blood pressure and diarrhea.
Your doctor might prescribe hormone-blocking drugs to reduce these symptoms.
Deciding what's best for you
Talk with your doctor about the
potential side effects and the possible benefits of all the treatments you're
considering. Balancing the risks with the benefits is the best way to choose a
treatment that's best for you.
By Mayo Clinic Staff