Hormone therapy is a treatment for cancer. It slows down or stops the growth of cancer cells that depend on hormones to grow and multiply.

It is a systemic therapy used in the treatment of certain kinds of breast cancer and prostate cancer that depend on sex hormones to grow. It is also used in the treatment of a few other cancers.

How does hormone therapy work against prostate cancer?

Hormone therapy for prostate cancer is also referred to as androgen suppression therapy or androgen deprivation therapy. It is part of the standard treatment for advanced and metastatic prostate cancer.

Its aim is to reduce levels of male hormones, called androgens, in the body. Androgens fuel the prostate cancer cells and stimulate them to grow.

The main androgens in the body are testosterone and dihydrotestosterone (DHT).  Most of the androgen hormones in man are made by the testicles though the adrenal glands also make some.

Hormone therapy either directly stops the production of testosterone or blocks its action on the prostate cancer cells.

If the androgen levels fall, prostate cancer begins to shrink or grow more slowly. However, hormonal treatment is not a cure but a good supportive treatment. It can give relief to the patient and increase his life by a few years.

Although it varies from case to case, on average, hormone therapy can stop the progress of cancer by two to three years.

Though this therapy is effective in controlling the growth of the cancer cells, it is not without side effects caused by loss of testosterone in the body. These side effects range from hot flashes, loss of bone density, mood swings, weight gain, and erectile dysfunction.

How long does it take for hormone therapy to work?

It usually takes a few weeks for the hormone therapy to start working and for you to start feeling the early benefits of the hormone therapy. It may take up to three months to experience the full effects.

It will also take time for your body to get used to hormone therapy. With the start of the treatment, you may experience certain side effects such as nausea, breast tenderness, and leg cramps.

Can hormone therapy stop working and prostate cancer spread?

In 85% to 90% of cases of advanced prostate cancer, hormone therapy shrinks the size of the tumor. However, this treatment does not last forever. Not all cancer cells rely on hormones to grow. Ultimately, the cells that do not depend on hormones will start spreading.

In many cases, prostate cancers eventually stop responding to hormone therapy and become resistant. They begin to grow in the low testosterone environment and this therapy has very little effect on controlling their growth.

Despite this, hormone therapy remains an important part of the management of advanced prostate cancer and metastasis.

Indications for hormone therapy in prostate cancer

  • In advanced and metastatic prostate cancer, to shrink the prostate cancer cells and slow their growth, which in effect will give symptomatic relief to the patient.
  • If the PSA levels remain high even after treatment
  • To make radiation therapy more effective
  • To reduce the chances of recurrence in those with a high risk of it after the treatment
  • In men who plan on surgery and want to shrink the tumor size to improve the success of surgery

Types of hormone therapy

Testosterone stimulates prostate cancer cells to grow and multiply. Hormone therapy blocks the production of testosterone, which in effect slows down the growth of the cancer cells.

There are different types of hormone therapies for prostate cancer, which help to do this and lower testicular androgen levels.

Orchiectomy (surgical castration)

Orchiectomy is an outpatient procedure and there is no need to admit the patient to the hospital.

The surgeon removes the testicles, where most of the androgens (testosterone and DHT) are produced in the body. This reduces the level of testosterone in the blood by 90% to 95%.

This causes most prostate cancers to shrink and stops the cancer cells from growing. No additional hormone therapy is required after orchiectomy.

Orchiectomy is permanent and irreversible and because of this, many men cannot accept to live without their testicles. They often choose to take treatment with hormonal therapy drugs (such as an LHRH agonist or antagonist). However, there is an option to have artificial testes inserted into the scrotum which look very much like normal ones.

Another option would be that the surgeon removes only the tissue in the testicles that produce androgens and not the entire testicle. This is called subcapsular orchiectomy and could be an option for those who want to maintain the testicles.

LHRH agonists

Luteinizing hormone-releasing hormone (LHRH) agonists (also called LHRH analogs or GnRH agonists) provide a conservative way to treat prostate cancer. They reduce the testosterone made by the testicles to the same extent as orchiectomy does.

Treatment with these drugs is called medical castration because of the similarity of action to orchiectomy. The testicles shrink over time and you may not be able to feel them after a period. LHRH agonists remain the usual first line of treatment.

LHRH agonists can be injected intramuscularly or placed as implants under the skin. Each of these drugs has a different dosage and can be given once a month, every three months or every six months, or even once a year.

LHRH agonists prevent the pituitary gland from secreting a hormone called luteinizing hormone (LH). When androgen levels in the body fall, the hypothalamus secretes the hormone, LHRH.

LHRH stimulates the pituitary gland to produce the luteinizing hormone, which in turn stimulates the testicles to produce testosterone.

LHRH agonists initially stimulate the production of luteinizing hormone. However, due to the continued presence of high levels of LHRH agonists, the pituitary gland stops producing luteinizing hormone. As a result, there is no stimulation to the testicles to produce testosterone.

Testosterone levels may flare up briefly for a few weeks after you receive an LHRH agonist because LHRH agonists cause the pituitary gland to secrete more luteinizing hormone before blocking its release.

The flare may worsen the clinical symptoms. This can be prevented by giving antiandrogen therapy along with the LHRH agonist for the first few weeks of treatment.

The LHRH agonists available include:

  • Leuprolide (Lupron, Eligard)
  • Goserelin (Zoladex)
  • Triptorelin (Trelstar)
  • Histrelin (Vantas)

LHRH antagonists

LHRH antagonists, another form of medical castration, lower the testosterone levels more quickly than LHRH agonists and find use in the treatment of advanced prostate cancer. Their mode of action is slightly different than LHRH agonists and they do not cause a flare-up of testosterone levels like the LHRH agonists.

The following two LHRH antagonists are approved to treat advanced prostate cancer in the United States:

  • Degarelix (Firmagon) is given as a monthly injection under the skin.
  • Relugolix (Orgovyx) is an oral pill to be taken once a day.

Anti-Androgens

Anti-androgens prevent androgens from binding to the androgen receptors in the prostate cancer cells. In the absence of testosterone (androgens), the cancer cells do not grow and multiply.

It should be noted that anti-androgens stop the androgens from binding to the receptor sites. They do not stop the production of androgens.

Examples of anti-androgens include:

  • Bicalutamide (Casodex)
  • Nilutamide (Nilandron)
  • Flutamide

Anti-androgens are rarely used alone. They may be added to the treatment if orchiectomy, LHRH agonist, or LHRH antagonist do not produce results by themselves. They are prescribed along with an LHRH agonist or LHRH antagonist.

How long can you have hormone treatment for prostate cancer?

Hormone therapy helps to shrink the size of the prostate and also cancer that has spread, making the treatment more effective. This therapy is given for up to six months before radiotherapy and during and after radiotherapy for up to three years.

However, opinions differ. According to one study, hormone therapy can be given for 18 months in selected cases without compromising on the survival or quality of life of the patient.

Notwithstanding what is said above, patients with high PSAs, over 1.5 ng/mL, should continue to receive long-term hormone therapy along with radiation therapy. It considerably improves their survival.

Hormone therapy side effects

Side effects of hormone therapy for prostate cancer can include:

  • Muscle atrophy
  • Increased body fat percentage
  • Loss of libido
  • Erectile dysfunction
  • Osteoporosis, which can lead to bone fractures
  • Hot flashes usually more intense over the face, neck, and chest.
  • Loss of body hair
  • Smaller genitalia
  • Growth of breast tissue
  • Tiredness
  • Behavior change
  • Metabolic disorders

Intermittent dosing

To minimize the side effects of hormone therapy medications, your doctor may put you on intermittent dosing. You take medications for certain periods of time till your PSA becomes very low. You might need to resume these medications if the disease recurs or progresses.

Early research shows this type of dosing may reduce side effects. However, the long-term survival benefits of intermittent therapy are yet to be fully studied.

Ideally, your doctor will prescribe intermittent dosing if your blood PSA levels become high without any other evidence of cancer having spread.

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