Prostate cancer cells require androgens — male sex hormones — to grow. Anti-androgens are a type of medication that binds to androgen receptors on prostate cancer cells to prevent their growth.

Anti-androgens are a type of hormone therapy or androgen suppression therapy. Doctors may also refer to anti-androgens as androgen receptor antagonists.

Doctors may prescribe anti-androgens alongside other treatments in advanced stages of prostate cancer or if other treatments are no longer effective.

This article will explain the goal of anti-androgen hormone therapy, the different types a doctor may prescribe, potential side effects, and the outlook for people receiving this treatment.

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Androgens are male sex hormones that are necessary for the prostate to grow and function properly. However, androgens also allow prostate cancer cells to grow.

For prostate cancer cells to grow, androgens attach to androgen receptors, a type of protein, on the prostate cancer cell. Anti-androgen drugs connect to androgen receptors to prevent cancer cells from growing.

According to the National Cancer Institute (NCI), the goal of anti-androgen medications is to lower levels of androgens in the body and prevent androgens supporting the growth of prostate cancer cells.

Reducing androgen levels or preventing androgens from attaching to prostate cancer cells can help to shrink the cancer or slow down cancer growth for a period of time. However, hormone therapy alone is not a cure for prostate cancer.

In later stages, when the cancer has spread to distant sites in the body, such as the bones, the goal of treatment is to control the cancer, relieve symptoms, and improve quality of life.

When will doctors prescribe anti-androgens?

Doctors may use anti-androgens as part of hormone therapy for treating advanced or stage 4 prostate cancer.

According to the NCI, doctors will not usually use anti-androgens as a stand-alone treatment but more often use them alongside other treatments.

A doctor may also prescribe anti-androgens if androgen deprivation therapy (ADT) stops being effective. ADT reduces the number of androgens the testicles produce and is usually the first-line hormone therapy for prostate cancer.

There are older and newer types of anti-androgens, also known as first-generation drugs or second-generation drugs. Both types come in the form of a daily pill.

First-generation anti-androgens for treating prostate cancer include:

  • flutamide (Eulexin)
  • bicalutamide (Casodex)
  • nilutamide (Nilandron)

Second-generation anti-androgens for treating prostate cancer include:

  • enzalutamide (Xtandi)
  • apalutamide (Erleada)
  • darolutamide (Nubeqa)

Second-generation drugs may be more effective at binding to androgen receptors and blocking their effects in a stronger, more specific way than first-generation anti-androgens.

According to the American Cancer Society (ACS), second-generation anti-androgens may also be effective even if first-line anti-androgens are not. Second-generation drugs can help treat prostate cancer that has not spread but is not responding to other hormone therapies.

Enzalutamide is suitable for treating prostate cancer that has spread. Apalutamide and darolutamide are suitable for treating cancer that has spread and is resistant to other types of hormone therapy.

The ACS lists the potential side effects of each type of anti-androgen. The side effects of first-generation anti-androgens may include:

The side effects of second-generation anti-androgens may include:

  • diarrhea
  • fatigue
  • rash
  • worsening of hot flashes
  • effects on the nervous system, such as dizziness or, in rare cases, seizures
  • heart problems
  • increased risk of falls

Darolutamide is the only second-generation anti-androgen to not cross the blood-brain barrier. This means the drug may cause fewer side effects relating to the central nervous system.

Anti-androgens are not the only treatment option for advanced prostate cancer. Other treatments include:

  • other types of hormone therapies
  • chemotherapy, which may be in combination with hormone therapy
  • external radiation therapy, which a doctor can follow with hormone therapy
  • bisphosphonates, which are drugs to treat bone disease if prostate cancer has spread to the bones
  • alpha emitter radiation therapy, where a doctor injects a radioactive substance into the body to destroy cancer cells
  • watchful waiting or active surveillance, in which a doctor will monitor the disease if it is progressing slowly or symptoms are unchanging rather than administering treatments that may come with risks
  • transurethral resection of the prostate (TURP), which is the surgical removal of prostate tissue
  • a clinical trial with radical prostatectomy, which is surgery to remove the prostate, and orchiectomy, which is surgery to remove one or both testicles

People can talk with a doctor to discuss which treatment options may be the most beneficial, as well as potential side effects. The ACS suggests speaking with different doctors to get different opinions on the most effective treatments.

A person may also discuss clinical trials with a doctor, and if there are any suitable trials they may be able to join.

Clinical trials are currently looking at new treatment options for prostate cancer, such as using cryosurgery to freeze cancer cells or high-energy sound waves to destroy cancer cells.

According to a 2019 article, newer anti-androgens such as enzalutamide and apalutamide may be an important part of treating castration-resistant prostate cancer (CRPC). CRPC is prostate cancer that continues to grow despite low testosterone levels.

Research in the article shows enzalutamide improves overall survival in metastatic CRPC before and after treatment with chemotherapy. Metastasis is the process of cancer cells spreading throughout the body.

Enzalutamide also improved metastatic-free survival in nonmetastatic CRPC.

Researchers in the article suggest that a combination of ADT and anti-androgen treatment may improve the effectiveness of treatment.

Prostate cancer cells require androgens to grow. Anti-androgen drugs bind to androgen receptors on prostate cancer cells to prevent or slow their growth.

Anti-androgens do not block the production of androgens, so doctors may use them after trying hormone therapies that prevent androgen production.

People may receive anti-androgen drugs in combination with other treatments, such as other hormone therapies, chemotherapy, or radiation therapy.