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Prostate cancer hormone therapy
treatment may use LHRH
agonists, also known as luteinizing hormone-releasing
hormone (LHRH) agonists or gonadotropin-releasing hormone
(GnRH)
agonists. Luteinizing hormone-releasing hormone and
gonadotropin-releasing hormone are essentially the same
chemicals which are released by the hypothalamus when
it detects lowering levels of testosterone.
An agonist is a chemical that mimics
a naturally-occurring substance in the body and produces
the same physiological effect. The agonist, therefore, will occupy
the cell receptors of the chemical it is mimicking.
An agonist has a longer biological half-life, meaning
the body takes longer to metabolize and eliminate the
agonist. The agonist therefore will occupy a receptor
for a longer period of time. Agonists are sometimes
referred to as analogues because they are inserted beneath
the skin where they continuously emit LHRH agonist of
GnRH agonist for a prostate
cancer treatment. LHRH and GnRH agonists are also
administered as an injection that can be performed in
a doctor’s office or at home.
The LHRH agonist mimics normal LHRH
and fills the receptors of the pituitary gland that
receive normal LHRH. For a period of 7 to 10 days, the
pituitary gland perceives the LHRH agonist as normal
LHRH and causes the testicles to produce large amounts
of testosterone. This sudden rise of testosterone is
known as “hormone
flare” or “tumor flare,”
which may be painful and possibly dangerous to patients
with advanced prostate cancer bone
metastasis. After 7 to 10 days, the
LHRH agonist still occupies the pituitary gland’s
receptors, whereas normal LHRH would have been metabolized.
The pituitary gland stops telling the testicles to make
testosterone. The level of hormone then drops by 90
to 95 percent, which is castration level. Use of LHRH
agonists is known as chemical or medical castration.
The LHRH agonists drugs include
leuprolide, goserelin, and triptorelin. These drugs
are also sometimes used to treat women’s health
problems including breast cancer. Leuprolide and goserelin
are available in the United States in both analogue
and injection form. Goserelin uses implants which are
injected under the skin of the upper right abdomen every
28 days or every twelve weeks. Goserelin can be injected
daily, once per month, once per 3 months, once per 4
months, and once per 12 months. Leuprolide comes with
patient instructions, so the administration of the hormone
therapy can be done at home. Patients who receive hormone
therapy daily are encouraged to receive injections around
the same time every day, and patients who receive their
injections after longer periods of time, are encouraged
to have their injections around the same time at the
end of their hormone therapy cycle. If a patient misses
a daily dose, they should receive the injection as soon
as possible.
Patients who have hormone therapy
kits in their homes must dispose of the needles properly.
Patients are also reminded that they are to use only
the needles provided with the kit because a different
needle could alter the dosage. Patients should keep
hormone therapy out of children’s reach and prevent
freezing, direct sunlight, and heat from possibly altering
the drug’s effectiveness.
Patients who have questions about
their treatment should not hesitate to speak with their
doctors or with a qualified prostate cancer nursing
specialist.
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