Topic Overview

Hormone therapy for prostate cancer is also known as androgen deprivation therapy (ADT). Prostate cancer cannot grow or survive without androgens, which include testosterone and other male hormones. Hormone therapy decreases the amount of androgens in a man's body. Reducing androgens can slow the growth of the cancer and even shrink the tumour.

Hormone therapy may be used:

• Along with (or after) radiation treatment when there is a higher risk of the cancer returning.
• When prostate cancer has come back.
• When prostate cancer is found outside the prostate in other parts of the body (metastatic) at the time of diagnosis.

When hormone therapy slows the growth of prostate cancer, a man's prostate-specific antigen (PSA) levels will go down. PSA tests will show if the treatment is working.

Medicines for hormone therapy

Taking medicine, such as luteinizing hormone-releasing hormone (LHRH) medicine, is one way to reduce androgens.

• LHRH agonists. These drugs stop the body from making testosterone. They include goserelin (Zoladex), histrelin (Vantas), leuprolide (Lupron), and triptorelin (Trelstar).
• LHRH antagonists. These drugs stop the body from making testosterone. They avoid the flare caused by LHRH agonists, which can make symptoms worse for several weeks. One LHRH antagonist is degarelix (Firmagon).
• Androgen inhibitors. These are medicines that block enzymes that the body needs to make testosterone. They include enzalutamide (Xtandi), ketoconazole and abiraterone (Zytiga), which is given along with prednisone.
• Antiandrogens. These drugs often are used along with LHRH agonists. Antiandrogens help block the body's supply of testosterone. There are steroidal antiandrogens and "pure" antiandrogens. The steroidal antiandrogens include megestrol (Megace). The "pure" or non-steroidal antiandrogens include bicalutamide (Casodex), flutamide, and nilutamide (Nilandron).

Other hormone therapies may include the use of medicines such as corticosteroids (dexamethasone, hydrocortisone, and prednisone), estrogen, and megestrol.

Surgery as hormone therapy

Another way, used much less often, is surgery to remove the testicles, also known as an orchiectomy. This surgery is considered to be hormone therapy. This is because removing the testicles, where more than 90% of the body's androgens are made, decreases testosterone levels. Removing the testicles may be the simplest way to reduce androgen levels, but it is permanent.

Effectiveness of hormone therapy

Hormone therapy usually works well at first to stop cancer growth. But in most cases, the cancer begins to grow again within a few years. At this point, the cancer is described as hormone-resistant, meaning it is not responding to standard hormone therapy. When this happens, other kinds of hormone treatments may be tried.

When hormone treatments no longer keep the cancer from growing, the cancer is called castrate-resistant prostate cancer (CRPC). Treatments that may be used to help men live longer include chemotherapy, immunotherapy, and medicines like enzalutamide.

Alternatives to conventional hormone therapy

• Intermittent androgen deprivation (IAD). This involves cycles of hormone therapy medicines. Taking breaks during hormone therapy gives men the chance to recover their ability to function sexually. It also gives relief from the other side effects of hormone therapy, including hot flashes and the effects on energy as well as bone and muscle mass. The long-term survival outcome of IAD compared to conventional ADT is not yet known.
• Antiandrogen monotherapy. Antiandrogens are medicines that block the action of androgens in the body. Antiandrogen monotherapy means taking antiandrogens without other hormone medicines.
• Combined androgen blockade (CAB). Sometimes androgen deprivation (orchiectomy or an LHRH agonist) and an antiandrogen are used together for treatment. This blocks the testosterone made by the testicles and the adrenal glands.

Side effects of hormone therapy

Medicine

In men who take medicine for hormone therapy, the side effects get worse over time. Some of the side effects will go away after the man stops taking the medicine. Side effects may include:

• Thin or brittle bones (osteoporosis).
• Increased body mass (BMI) and higher levels of fats in the blood.
• Reduced muscle mass.
• Low red blood cell count (anaemia) and fatigue.
• Increased risk for diabetes, and heart disease.
• Emotional ups and downs.
• Diarrhea, nausea or vomiting.

Other side effects may include hot flashes, erection problems and reduced sex drive, breast enlargement, and cognitive impairment. Some men may experience depression.

Surgery

In men who have surgery for hormone therapy, two side effects happen right away and are permanent—the man becomes sterile and loses interest in sex. Other than those two side effects, surgery tends to have fewer side effects than medicine.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems).

Hormone therapy and quality of life

The side effects of hormone therapy for prostate cancer often affect a man's quality of life. But there are treatments that can help with some of the side effects listed above. For example, exercise can help counteract the loss of muscle mass and will help with fatigue. There are medicines that can help with hot flashes, nausea, diarrhea, and bone loss. Low-dose radiation or taking tamoxifen may help prevent or reduce breast enlargement. For men with depression, counselling and medicine may help. For more information, see the topic Depression.

Above all, talk with your doctor about any of the symptoms you have while you are taking hormone therapy. Your doctor may know about a local support group for men who have prostate cancer.