Antiandrogens for Prostate Cancer

Search Knowledgebase

Topic Contents

Antiandrogens for Prostate Cancer


Generic NameBrand Name

How It Works

Androgens are hormones. Antiandrogens are drugs that block the action of these hormones. In prostate cancer, they block the action of testosterone made by the testicles and/or adrenal glands. This usually slows prostate cancer growth.

There are steroidal antiandrogens and "pure" antiandrogens. The steroidal antiandrogens include megestrol (Megace). The "pure" or non-steroidal antiandrogens include bicalutamide (Casodex), flutamide (Euflex), and nilutamide (Anandron).

Why It Is Used

An antiandrogen is often added to luteinizing hormone-releasing hormone (LH-RH) agonist therapy to prevent a rise in testosterone at the beginning of LH-RH agonist therapy. (The rise in testosterone can cause a tumour flare with bone pain, urinary blockage, or other symptoms of rapid cancer growth. But this growth does shrink over time.)

Antiandrogens can be used along with surgery to remove the testicles (orchiectomy).

Antiandrogens may be used before or after radiation for men with intermediate-risk prostate cancer.

Antiandrogens are often used in combination with other hormone therapy to block the supply of testosterone. This is done to slow the growth of advanced prostate cancer and ease severe bone pain caused by the spread of cancer to the bones.

How Well It Works

Studies show that taking antiandrogens may provide a small benefit for men who have metastatic prostate cancer and are also taking an LH-RH agonist.1

Side Effects

Side effects from antiandrogen treatment may include:

  • Nausea.
  • Breast enlargement (gynecomastia).
  • Diarrhea.
  • Low red blood cell count (anemia).
  • Decreased sex drive.
  • Erection problems.
  • Liver problems. Some cases of serious liver problems have been reported.

Long-term treatment with antiandrogens may cause osteoporosis, which causes bones to become brittle and break more easily. Your doctor may prescribe a bisphosphonate medicine. Zoledronic acid is a bisphosphonate specifically designed for people who are receiving treatment for metastatic cancer.

One study found that men with metastatic prostate cancer who were treated with zoledronic acid had fewer bone problems and less pain than men who weren't treated with zoledronic acid. They also had a longer time before any bone problems began.2

For more information on prevention of and medicine for bone thinning, see the topic Osteoporosis.

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

What To Think About

Antiandrogens may improve a man's quality of life when bone pain caused by prostate cancer is severe.

Sometimes flutamide has an effect called a “withdrawal response” in which the tumour shrinks and the PSA level improves when a man stops taking the medicine.

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



  1. Zelefsky MJ, et al. (2008). Cancer of the prostate. In VT DeVita Jr et al., eds., Devita, Hellman, and Rosenberg's Cancer: Principles and Practice of Oncology, 8th ed., vol. 1, pp. 1392–1452. Philadelphia: Lippincott Williams and Wilkins.
  2. National Comprehensive Cancer Network (2009). Prostate cancer. NCCN Clinical Practice Guidelines in Oncology, version 2.2009. Available online:


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

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.