The short answer
Prostate cancers need male hormones called androgens to grow. Hormone therapy lowers androgen levels or blocks their action to slow the cancer. It is used at different stages, and its side effects can be reduced with exercise and other steps.
Early prostate cancers need androgens (male hormones) such as testosterone to grow.
Hormone therapy lowers androgen levels or blocks their action to slow the cancer.
The most common first type is androgen deprivation therapy (ADT), which reduces testosterone from the testicles.
Over time, many prostate cancers become castration resistant and keep growing despite low androgen levels.
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The full explanation.
The simple version
Male sex hormones, called androgens, control the development and upkeep of male characteristics. The most common androgens are testosterone and dihydrotestosterone (DHT). Androgens are needed for the normal prostate to work — but they are also needed for prostate cancers to grow.
Early in their development, prostate cancers need androgens to grow. Hormone therapy lowers androgen levels or blocks androgen action to slow the growth of these cancers.
Hormone therapy works by cutting off the androgens that prostate cancer needs to grow.
How the cancer responds over time
Prostate cancers that still depend on androgens are called castration sensitive (also androgen dependent or hormone sensitive). Hormone therapy can slow them.
However, most prostate cancers eventually stop responding and become castration resistant. This means they keep growing even when androgen levels in the body are extremely low. Some newer hormone therapies are available to treat cancer that has become castration resistant.
The main types
Hormone therapy can block the production or use of androgens in several ways:
Reducing androgen production by the testicles. This is the most common form, called androgen deprivation therapy (ADT), and usually the first type people receive. It includes:
- Orchiectomy, surgery to remove both testicles, which can lower testosterone by 90% to 95%. This is permanent.
- LHRH agonists, drugs that eventually cause the pituitary gland to stop signaling the testicles to make androgens. This is called medical or chemical castration and is reversible. They are given by injection or implant. When first started, they can briefly raise testosterone (a "testosterone flare").
- LHRH antagonists, another form of medical castration that does not cause a flare.
Blocking the action of androgens (androgen receptor blockers). These compete with androgens to bind to androgen receptors, keeping androgens from fueling cancer growth. They are usually used together with ADT and are given as pills.
Blocking androgen production throughout the body (androgen synthesis inhibitors). These stop androgen production not only by the testicles but also by the adrenal glands and prostate cancer cells. They are given as pills.
How it is used
Hormone therapy may be used in several ways for castration-sensitive prostate cancer:
- Early-stage cancer with higher risk of recurrence. Men having radiation for early-stage cancer with an intermediate or high risk of recurrence often receive ADT as well.
- Relapsed or recurrent cancer. Hormone therapy is often used alone after a recurrence following radiation or surgery.
- Advanced or metastatic cancer. ADT was long the standard, but men are now often treated with ADT plus another hormone therapy or chemotherapy.
- Easing symptoms. Hormone therapy is sometimes used alone to prevent or relieve local symptoms in men who are not candidates for surgery or radiation.
To check whether hormone therapy is working, men who take it for more than a few months are regularly tested for the level of PSA (prostate-specific antigen) in their blood. A rising PSA may mean the cancer has started growing again or become resistant.
Side effects and how to reduce them
Because androgens affect many organs, ADT can cause a wide range of side effects, including loss of interest in sex, erectile dysfunction, hot flashes, loss of bone density and fractures, loss of muscle mass and strength, changes in blood fats, insulin resistance, weight gain, mood swings, fatigue, and growth of breast tissue. The risk increases the longer you are on hormone therapy.
Some side effects can be reduced. Men who lose bone mass may be prescribed drugs to slow or reverse it. Exercise may help reduce bone loss, muscle loss, weight gain, fatigue, and insulin resistance. Most sexual and emotional side effects eventually go away if hormone therapy is stopped, though for older men or those treated for a long time, some changes may not fully disappear, and physical changes such as bone loss may remain.
Many side effects ease after hormone therapy stops, and exercise and certain medicines can help along the way.
Words to know
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Common questions
▸How does hormone therapy work against prostate cancer?
Early in their development, prostate cancers need androgens (male hormones) to grow. Hormone therapies decrease androgen levels or block androgen action, which can slow the growth of these cancers. Such cancers are called castration sensitive or hormone sensitive.
▸What is androgen deprivation therapy (ADT)?
ADT is the most common form of hormone therapy for prostate cancer and usually the first type people receive. It reduces androgen production by the testicles. It can be done by surgery to remove the testicles (orchiectomy) or with drugs such as LHRH agonists or LHRH antagonists.
▸What are the main types of hormone therapy for prostate cancer?
Treatments can reduce androgen production by the testicles (ADT), block the action of androgens in the body (androgen receptor blockers), or block androgen production throughout the body (androgen synthesis inhibitors). They are given as injections, implants, or pills depending on the drug.
▸Does hormone therapy stop working over time?
Most prostate cancers eventually stop responding to hormone therapy and become castration resistant, meaning they keep growing even when androgen levels are very low. Some newer hormone therapies can be used to treat cancer that has become castration resistant.
▸What are the side effects of hormone therapy for prostate cancer?
Because androgens affect many organs, side effects can include loss of interest in sex, erectile dysfunction, hot flashes, loss of bone density and fractures, loss of muscle mass, weight gain, mood swings, fatigue, and growth of breast tissue. The risk increases the longer you are on hormone therapy.
▸Can side effects be reduced?
Yes. Men who lose bone mass may be given drugs to slow or reverse it. Exercise may help reduce bone loss, muscle loss, weight gain, fatigue, and insulin resistance. Most sexual and emotional side effects eventually go away if hormone therapy is stopped, though some changes may remain.
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