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.
steroidal antiandrogens and "pure" antiandrogens. The steroidal antiandrogens
include megestrol (Megace). The "pure" or nonsteroidal antiandrogens include
bicalutamide (Casodex), flutamide, and nilutamide (Nilandron).
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 tumor 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 from antiandrogen treatment
- Breast enlargement (gynecomastia).
red blood cell count (anemia).
- Decreased sex
- 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
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
information on prevention of and medicine for bone thinning, see the topic
See Drug Reference for a
full list of side effects. (Drug Reference is not available in all
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 tumor shrinks and the PSA level improves when a man stops taking the
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
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.
National Comprehensive Cancer Network (2009). Prostate cancer. NCCN Clinical Practice Guidelines in Oncology, version 2.2009. Available online: