Hormonal therapy for prostate cancer
Hormonal therapy is often used to treat prostate cancer. It is a treatment that adds, blocks or removes hormones. Hormones are substances that control some body functions, including how cells act and grow. Changing the levels of hormones or blocking certain hormones can slow the growth and spread of prostate cancer cells. Drugs or surgery can be used to change hormone levels or block their effects.
Hormonal therapy alone can’t cure prostate cancer, but it can shrink tumours, slow the growth of cancer cells and help men live longer. You may have hormonal therapy to:
- treat advanced or recurrent prostate cancer – this includes a biochemical recurrence of prostate cancer where the prostate-specific antigen (PSA) level starts to rise quickly after initial treatment but there are no other signs of cancer
- shrink a tumour before other treatments (called neoadjuvant therapy), such as surgery or radiation therapy
- help radiation therapy work better (called concomitant therapy)
- control cancer cells left behind after surgery or radiation therapy and reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
- relieve pain or control the symptoms of advanced prostate cancer (called palliative therapy)
Your healthcare team will consider your personal needs to plan your hormonal therapy. Some men may start hormonal therapy soon after they are diagnosed. Other men may not start treatment until the symptoms of prostate cancer get worse. Some men may be on hormonal therapy longer than other men. Some men will start and stop hormonal therapy (called intermittent hormonal therapy), while others will take it continuously for a long time.
How hormonal therapy works
Prostate cancer cells use androgens to help them grow. An androgen is a type of hormone that controls the development of male physical traits, such as a deep voice and the growth of hair on the body and face. The main androgens are testosterone and dihydrotestosterone (DHT). These hormones are made mainly by the testicles. Hormonal therapy for prostate cancer blocks the production or effects of these hormones, so it is also called androgen deprivation therapy (ADT) or androgen suppression therapy.
Hormonal therapy can stop working over time so that prostate cancer begins to grow again (called castrate-resistant prostate cancer). When this happens, doctors may offer other hormonal therapies or other treatments. They can’t predict how long hormonal therapy will work, so you will have regular blood tests to check PSA and testosterone levels. If the PSA starts to rise and the testosterone level is low, it may mean the cancer has started to grow again.
Hormonal therapies commonly used for prostate cancer
The following are hormonal therapies used to treat prostate cancer.
Luteinizing hormone–releasing hormone (LHRH) agonists
LHRH (also called gonadotropin-releasing hormone, or GnRH) is made in an area of the brain called the hypothalamus. This hormone stimulates the pituitary gland to make luteinizing hormone (LH), which in turn stimulates the testicles to make testosterone.
LHRH agonists (also called GnRH agonists) are drugs that cause the pituitary gland to make extra LH. Eventually the pituitary gland stops responding to the LHRH agonist and the pituitary stops releasing LH. As a result, the testicles stop making testosterone. The lowered amount of testosterone then slows the growth of prostate cancer cells.
The most common LHRH agonists used to treat prostate cancer are:
- leuprolide (Lupron, Lupron depot, Eligard)
- goserelin (Zoladex)
- triptorelin (Trelstar)
- histrelin (Vantas)
These drugs are given either as an injection or as an implant placed under the skin. Different drugs are given on schedules that vary from once a month to once a year.
When a man first takes LHRH agonists, they cause a temporary rise in testosterone that lasts for about a week. This rise may cause symptoms to worsen for a few weeks. This is called a tumour flare reaction. Your doctor will likely prescribe another type of hormonal therapy called an anti-androgen to help prevent a tumour flare reaction. Anti-androgens are usually started at the same time as LHRH agonists and are taken for a few weeks.
Luteinizing hormone–releasing hormone (LHRH) antagonists
LHRH antagonists (also called GnRH antagonists) are drugs that stop the pituitary gland from making LH. This causes the testicles to stop making testosterone, which slows the growth of prostate cancer cells.
LHRH antagonists usually lower testosterone levels more quickly than LHRH agonists. They also don’t cause a tumour flare reaction.
The LHRH antagonist used to treat prostate cancer is degarelix (Firmagon). It is given as a monthly injection.
Anti-androgens stop the production of androgens or block the action of androgens. They attach to androgen receptors on prostate cancer cells and prevent them from using testosterone to grow.
Anti-androgens are given by mouth in pill or liquid form. The anti-androgens that are tried first for prostate cancer (called first-generation anti-androgens) are:
- bicalutamide (Casodex)
- flutamide (Euflex)
- nilutamide (Anandron)
If first-generation anti-androgens stop working, the following second-generation anti-androgens are used:
- abiraterone acetate (Zytiga) with prednisone
- enzalutamide (Xtandi)
Ketoconazole (Nizoral) and aminoglutethimide (Cytraden) are 2 other second-generation anti-androgens, but they have more side effects and are not as effective as the other drugs so they are rarely used.
Anti-androgen drugs usually aren’t given alone to treat prostate cancer. They may be used along with an orchiectomy or an LHRH agonist or LHRH antagonist (called combined androgen blockade, or CAB) as the main treatment for prostate cancer. Anti-androgens can also be given if the cancer starts to grow after an orchiectomy or while you are taking an LHRH agonist or LHRH antagonist (called castrate-resistant prostate cancer). These drugs can also be used to prevent a tumour flare reaction if you are taking LHRH agonists.
If prostate cancer stops responding to anti-androgens and the cancer begins to grow again, anti-androgen therapy is stopped. Sometimes prostate cancer stops growing when anti-androgens are stopped, but doctors aren’t sure why this happens. This is called an anti-androgen withdrawal effect.
An orchiectomy (also called surgical castration) is surgery to remove the testicles. Removing the testicles reduces the amount of testosterone in the body, which makes most prostate cancers shrink.
The advantage of an orchiectomy is that you don’t have to take pills or get an injection regularly. But some men may worry that removing their testicles will make them feel like less of a man. In fact, the testicles get much smaller with any form of hormone therapy, including hormonal drug therapy. But most men still choose to take drugs instead of having an orchiectomy.
Estrogen is a hormone that causes female sex characteristics to develop. It can be used to treat prostate cancer by lowering the level of androgens in the body. Estrogens are sometimes used when other hormonal therapies stop working. They are given daily as a pill.
Side effects can happen with any type of treatment for prostate cancer, but everyone’s experience is different. Some men have many side effects. Other men have few or none at all.
If you develop side effects, they can happen any time during, immediately after or a few days or weeks after hormonal therapy. Sometimes late side effects develop months or years after hormonal therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.
Side effects of hormonal therapy will depend mainly on the type of hormonal therapy, the dose of a drug or combination of drugs, if any other treatments are given and your overall health. Some common side effects of hormonal therapy for prostate cancer are:
- sexual problems, such as low sex drive, erectile dysfunction or shrinkage of the testicles and penis
- menopausal-like symptoms, including hot flashes and mood swings
- breast tenderness and growth of breast tissue (called gynecomastia)
- weight gain
- loss of muscle and physical strength
- bone thinning (called osteoporosis) and bone fractures
- depression, trouble concentrating and memory problems
- heart problems
Tell your healthcare team if you have these side effects or others you think might be from hormonal therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.
Information about specific cancer drugs
Details on specific drugs change regularly. Find out more about sources of drug information and where to get details on specific drugs.
Questions to ask about hormonal therapy
The main endocrine system gland at the base of the brain that produces hormones to control other glands and many body functions, including growth.
Also called the hypophysis.
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