A type of treatment that interrupts the supply of male hormones (such as testosterone) that encourage cancer growth, either by medication or by surgery to remove the testicles (the main source of testosterone). This treatment is used in some types of male reproductive cancer (such as prostate cancer). Hormonal therapy may be used in combination with radiation treatment or prostatectomy (removal of the prostate) in both early and advanced prostate cancers.
Hormonal therapy also may be used to relieve the pain and other symptoms of advanced disease. Although hormonal therapy cannot cure cancer, it usually shrinks the tumor and slows the advance of disease.
In surgical castration, surgeons remove the testicles (orchiectomy) through a small incision in the scrotum. The surgery is permanent and the effects cannot be reversed. In medical castration (or chemical castration), doctors administer a luteinizing hormone-releasing hormone analog (LHRHa) such as leuprolide, goserelin, or buserelin. These drugs work by switching off the production of male hormones in the testicles by reducing the level of luteinizing hormone. This hormone is produced by the pituitary gland at the base of the brain. This type of castration is reversible; if treatment is stopped, testosterone is produced once again. Most men who undergo castration (surgical or medical) experience a loss of sexual desire and hot flushes.
After surgery to remove the testicles, or treatment with an LHRH analog, the testicles no longer produce testosterone. However, the adrenal glands still produce small amounts of male hormones. For this reason, the patient also may be given antiandrogens such as ketoconazole or aminoglutethimide, flutamide or bicalutamide to block the effects of any remaining male hormones. Combination hormone therapy involving a complete blockage of androgen production including orchiectomy or LHRH analogs, plus the use of antiandrogens drugs is also called total hormonal ablation, total androgen blockade, or total androgen ablation.
Doctors are not sure whether total androgen blockade is more effective than orchiectomy or LHRH analogs alone. Prostate cancer that has spread to other parts of the body usually can be controlled with a hormonal therapy for some time (often years). Although hormone therapy may delay the progression of prostate cancer, however, its influence on survival is not well known. Eventually, most prostate cancers are able to grow with very little or no male hormones. When this happens, hormonal therapy is no longer effective, and the doctor may suggest other forms of treatment that are under study.
Men who have high-grade prostate cancer (Gleason score above 7) or cancer in the seminal vesicles or lymph nodes at surgery and who experience a rise in prostate-specific antigen (prostate-specific antigen) level within two years of prostatectomy probably have metastatic disease and are candidates for hormone therapy.
The side effects of hormonal therapy depend largely on the type of treatment. Orchiectomy and LHRH analogs often cause side effects such as impotence, hot flashes, and loss of sexual desire. When first used, an LHRH analog may make a patient’s symptoms worse for a short time; this temporary problem is called flare. Gradually, however, the treatment causes the testosterone level to fall. Without testosterone, tumor growth slows and the patient’s condition improves. (To prevent flare, the doctor may give the man an antiandrogen for a while along with the LHRH analog.)
Antiandrogens can cause nausea, vomiting, diarrhea, or breast growth or tenderness. If used over a long period, ketoconazole may cause liver problems, and aminoglutethimide can cause skin rashes. Men who receive total androgen blockade may experience more side effects than men who receive a single method of hormonal therapy. Any method of hormonal therapy that lowers androgen levels can contribute to weakening of the bones in older men.
Hormone-Refractory Prostate Cancer
When a man’s prostate-specific antigen level continues to increase despite all forms of hormone therapy, the cancer is called hormone refractory, meaning it is resistant to hormone therapy. In this case, a doctor may prescribe chemotherapy.
Hormonal therapy may be given before prostatectomy or radiation therapy to reduce the size of the prostate; this is called neoadjuvant hormone therapy. The treatment also may be used after prostatectomy or radiation (adjuvant hormone therapy) to affect any cancer cells that remain after prostatectomy or radiation therapy.