Hormone Therapy for Prostate Cancer
Male sex hormones (androgens), especially testosterone, are required to maintain the size and function of the prostate. As a result, a treatment option for intermediate-and high-risk prostate cancers is to interfere with the effects of androgens by blocking the testicles' production of testosterone or blocking the receptor to which testosterone attaches. Hormone therapy causes the cancer to regress and is used routinely along with radiation therapy for the treatment of intermediate- and high-risk cancers and in the management of metastatic prostate cancer.
When used for the treatment of metastatic prostate cancer, prostate cancer cells eventually bypass the testosterone block by manufacturing their own needed androgens through alternate pathways. Therefore, although hormone therapy is useful in treating prostate cancer, it does not offer a cure. Hormone therapy used to be reserved for men whose prostate cancer had spread to the lymph nodes, bone, or other sites. Now it is often given preemptively to men whose cancer is expected to spread after radiation or surgery—for example, a man with a rapidly rising PSA level.
For men with prostate cancer that has spread to lymph nodes or bones, the goals of hormone therapy are to prolong life and relieve symptoms such as bone pain or urinary tract problems. Hormone therapy prolongs life for many of these men; about 25 percent will live five or more years.
PSA level helps predict survival in men with metastatic prostate cancer. A PSA of less than 4 ng/mL within three to six months of initiating hormone therapy predicts a good response to the treatment. A rising PSA level during hormone therapy indicates that the disease is progressing.
No consensus exists concerning when hormone therapy should begin. Whether hormone treatment is started before or after cancer progression is documented on a bone scan may or may not affect how long a man survives.
Moreover, all effective forms of hormone therapy have significant side effects. These side effects may include ED (which affects about 90 percent of men), loss of libido, breast enlargement, weight gain, loss of muscle mass, osteoporosis (decreased bone mass), fatigue, a decline in cognitive function, and hot flashes.
Hormone therapy also increases the risk of cardiovascular disease in some men, and the harm may outweigh the benefit, especially for men with localized cancer who are unlikely to experience improved cancer control when hormone therapy is used in addition to other management options. Because no hormone treatment can cure the disease regardless of when treatment begins, side effects must be given serious consideration when deciding when to start the treatment.
There are many options for hormone therapy of prostate cancer. Surgical castration (surgical removal of the testes, which produce about 95 percent of a man's testosterone) was the main approach prior to the 1980s. Today the most common approach is the use of medications that interfere with the production of testosterone by the testes (medical castration) or block it from attaching to receptors inside cancer cells. These medications include luteinizing hormone-releasing hormone (LHRH) agonists, also known as gonadotropin-releasing hormone (GnRH) agonists; LHRH antagonists, also known as GnRH receptor antagonists; and antiandrogens. Whether accomplished surgically or medically, hormone therapy prolongs the life of men with metastatic prostate cancer.