Hormone therapy for prostate cancer

Hormone therapy is often used to treat prostate cancer. Hormone therapy for prostate cancer works by reducing the amount of androgens (male hormones) or blocking androgens from being used.

Androgens, such as testosterone, help prostate cancer cells to grow. Androgens control the development of male physical traits, such as a deep voice and the growth of hair on the body and face. Androgens are made mainly by the testicles.

Drugs or surgery can be used to block the production or effects of androgens like testosterone. Hormone therapy alone can't cure prostate cancer, but it can shrink tumours, slow the growth of cancer cells and help you live longer.

You may have hormone therapy to:

• treat cancer that has spread outside of the prostate (called locally advanced or metastatic prostate cancer)
• treat prostate cancer that comes back after treatment (called recurrent prostate cancer)
• treat prostate cancer along with radiation therapy for cancer that has a higher risk of coming back
• shrink a tumour before other treatments (called neoadjuvant therapy), such as surgery or radiation therapy

Your healthcare team will consider your personal needs to plan your hormone therapy. You may start hormone therapy soon after you are diagnosed. Or you may not start treatment until the symptoms of prostate cancer get worse. You may be on hormone therapy longer than others. You may start and stop hormone therapy (called intermittent hormone therapy), while others will take it continuously for a long time.

Hormone therapy can stop working over time so that prostate cancer begins to grow again (called castration-resistant prostate cancer). When this happens, doctors may offer other hormone therapies or other treatments. They can't predict how long hormone therapy will work, so you will have regular blood tests to check prostate-specific antigen (PSA) and testosterone levels. If the PSA level starts to rise and the testosterone level is low, it may mean that the cancer has started to grow again.

There are different types of hormone therapy used to treat prostate cancer:

Luteinizing hormone–releasing hormone (LHRH) agonists are drugs that stop the testicles from making testosterone. LHRH agonists are also called LHRH analogs or gonadotropin-releasing hormone (GnRH) agonists.

The most common LHRH agonists used to treat prostate cancer are:

• leuprolide (Lupron, Lupron depot, Eligard)
• goserelin (Zoladex)
• triptorelin (Trelstar)

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 you first take 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 hormone 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.

LHRH antagonists (also called GnRH antagonists) are drugs that stop the pituitary gland from making LH. This causes the testicles to stop making testosterone. 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.

Androgen synthesis inhibitors block enzymes that the body needs to make testosterone.

Androgen synthesis inhibitors include abiraterone (Zytiga). They may be used to treat advanced prostate cancers. Because these drugs can also block the production of cortisol, you will need to take a corticosteroid such as prednisone, methyl-prednisone or hydrocortisone.

Anti-androgens block the use of testosterone. They attach to androgen receptors on prostate cancer cells and prevent them from using testosterone to grow.

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 castration-resistant prostate cancer). These drugs can also be used to prevent a tumour flare reaction if you are taking LHRH agonists. Because these drugs can also block the use of cortisol, you will need to take a corticosteroid such as prednisone or hydrocortisone.

Anti-androgens are given by mouth in pill or liquid form. The anti-androgens that are most commonly used be to treat prostate cancer are:

• bicalutamide (Casodex)
• flutamide
• nilutamide (Anandron)
• apalutamide (Erleada)
• enzalutamide (Xtandi)
• darolutamide (Nubeqa)

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. An orchiectomy is not commonly used to treat prostate cancer.

Prostate cancer treatment has become very personalized. For that reason there are several different ways of using hormone therapy to treat prostate cancer.

Doctors don't always agree on when is best to start hormone therapy. Some think it works better if it's started as soon as possible, even if you aren't having symptoms. But others feel that hormone therapy shouldn't be started until you have symptoms.

Many prostate cancers treated with hormone therapy become resistant to this treatment after months or years. For this reason, some doctors may use intermittent (on-again, off-again) treatment. This also gives you a break from side effects of hormone therapy.

Combined androgen blockade combines different types of hormone therapies. An androgen synthesis inhibitor or anti-androgen is combined with an orchiectomy, LHRH agonist or LHRH antagonist to maximize the blocking of androgens.

Triple androgen blockade is when a 5-alpha reductase inhibitor such as finasteride (Proscar) or dutasteride (Avodart) is given with combined androgen blockade.

Side effects can happen with any type of treatment for prostate cancer, but everyone's experience is different. Some people have many side effects. Other people 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 hormone therapy. Sometimes late side effects develop months or years after hormone 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 hormone therapy will depend mainly on the type of hormone 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 hormone therapy for prostate cancer are:

• sexual problems (low sex drive, erectile dysfunction or shrinkage of the testicles and penis)
• hot flashes
• mood swings
• breast tenderness and growth of breast tissue (called gynecomastia)
• loss of muscle and physical strength
• bone thinning (called osteoporosis) and bone fractures
• fluid retention
• joint or muscle pain
• fatigue
• diarrhea
• constipation
• high blood pressure
• headache
• upset stomach
• nausea
• depression, trouble concentrating and memory problems
• increased cholesterol
• heart problems

Tell your healthcare team if you have these side effects or others you think might be from hormone therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Details on specific drugs change regularly. Find out more about sources of drug information and where to get details on specific drugs.

Find out more about hormonal therapy and side effects of hormonal therapy. To make the decisions that are right for you, ask your healthcare team questions about hormonal therapy.