Hormone Treatment for Prostate Cancer

Hormone treatment is also called “androgen deprivation therapy (ADT)” or “androgen suppression therapy.” The aim is to reduce male hormones called androgens or stop their effects on prostate cancer cells.

Androgens trigger prostate cancer cell proliferation and spread. The main androgens are testosterone and dihydrotestosterone. Most are produced by the testicles, but the adrenal glands above the kidneys also produce some. Lowering androgen levels or preventing prostate cancer cells from using them often shrinks cancers or slows growth for a time. Hormone treatment alone, however, does not completely cure prostate cancer.

When hormone treatment is used

It may be used in these situations:

• If prostate cancer has spread too far to be cured by surgery or radiotherapy, or if these cannot be performed for various reasons
• If cancer recurs after surgery or radiotherapy
• With radiation treatment if recurrence risk is high (patients are classified as low, intermediate or high risk according to Gleason score, PSA level and/or spread beyond the prostate; recurrence is more likely in the high-risk group) 
• Before radiotherapy to shrink cancer further and increase treatment effectiveness

Types of hormone treatment

Many hormone treatment types are used for prostate cancer.

Treatments reducing androgen levels

Orchiectomy (surgical castration)

The testicles are the major androgen source. They are surgically removed in this method, stopping or shrinking many prostate cancers temporarily. It is a day-case operation and may be the simplest, cheapest hormone treatment.

LHRH agonists

These reduce testosterone production in the testicles. Treatment is sometimes called chemical or medical castration because it reduces androgen levels as effectively as orchiectomy.

LHRH agonists are generally injected monthly or every 3 months. The most commonly used drugs in this group in our country are Leuprolide (Eligard) and Goserelin (Zoladex).

When LHRH agonists are first given, testosterone levels rapidly rise and then fall. This is called the flare effect. To prevent this effect, several weeks before starting LHRH agonists, drugs called antiandrogens should be started (we will discuss these drugs in our next article).

LHRH antagonists

Degarelix (Firmagon) is an LHRH antagonist. It acts like LHRH agonists but lowers testosterone faster and causes no flare.

It treats advanced prostate cancer through monthly subcutaneous injections.

CYP17 inhibitor

LHRH agonists and antagonists attempt to inhibit androgen production in the testicles. However, if prostate cancer has spread throughout the body, these cells continue producing small amounts of growth-stimulating androgens. Abiraterone (Zytiga) inhibits the enzyme CYP17, blocking androgen production not only in testicles but also adrenal glands and metastatic prostate cancer cells. Abiraterone is a daily pill used for advanced hormone-resistant prostate cancer.

Our continuation article discusses another hormone treatment type, drugs inhibiting androgen action (antiandrogens), their possible side effects and how to cope:

- Hormone Treatment for Prostate Cancer – 2