LH-RH Agonists/GnRH Agonists for Prostate Cancer

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LH-RH Agonists/GnRH Agonists for Prostate Cancer


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How It Works

Luteinizing hormone-releasing hormone (LH-RH) agonists and gonadotropin-releasing hormone (GnRH) agonists are hormone therapy drugs that lower the production of testosterone in a man's body. This drop in testosterone usually slows or stops the growth of prostate cancer for a period of time.

These drugs work by causing the pituitary gland to release the hormones that cause the testicles and adrenal glands to make testosterone. The pituitary gland then runs out of its hormones, and testosterone production drops.

These drugs are usually given by injection. They may be given once a month, once every 3 to 4 months, or once a year.

Why It Is Used

LH-RH and GnRH agonists are used to treat advanced prostate cancer. They are often used with other treatments, such as surgery or radiation therapy.

LH-RH and GnRH agonist therapy can also be used to relieve pain caused by metastatic prostate cancer.

How Well It Works

LH-RH agonist therapy improves a man's chances of living longer. When combined with radiation therapy or surgery to remove the prostate, LH-RH therapy may improve survival in men who have locally advanced cancer.

Treatment with LH-RH agonists may control severe pain caused by metastatic prostate cancer and may improve a man's quality of life. LH-RH agonists may be able to reduce bone fractures and spinal cord compression caused by metastatic disease if treatment is started as soon as cancer progression is evident.1

Side Effects

Side effects from LH-RH agonists and GnRH agonists may include:2

These drugs work on the pituitary gland to release its hormones. So the testicles may temporarily produce extra testosterone, causing a temporary growth in the tumour. This is called a tumour flare. Tumour flare may be accompanied by bone pain, urinary blockage, or other symptoms of rapid cancer growth. This may mean that the drug is working. And although the tumour may grow at first, it will shrink over time. Tumour flare can be prevented by taking a different hormone drug called an antiandrogen before or during treatment with the LH-RH agonist.

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

What To Think About

Hot flashes are a problem with hormone therapy. Hot flashes may last for years. Talk with your doctor about medicines and treatments that may help.

If you get hot flashes from your LH-RH treatment, your doctor may prescribe cyproterone (Androcur) to help treat them.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. National Cancer Institute (2010): Prostate Cancer Treatment (PDQ)—Health Professional Version. Available online: http://www.nci.nih.gov/cancertopics/pdq/treatment/prostate/healthprofessional.
  2. Nelson JB (2007). Hormone therapy for prostate cancer. In AJ Wein, ed., Campbell-Walsh Urology, 9th ed., vol. 3, pp. 3082–3100. Philadelphia: Saunders Elsevier.


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer J. Curtis Nickel, MD, FRCSC - Urology
Last Revised September 27, 2010

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