Treating Advanced Prostate Cancer
Luteinizing hormone-releasing hormone (LHRH) antagonists
These drugs have been approved for use as endocrine therapy in patients with advanced prostate cancer. LHRH antagonists lower testosterone levels more quickly than LHRH analogs. In addition, they don't cause a tumor flare (temporary rise in testosterone levels) as do LHRH analogs. But they carry the risk of serious and potentially life-threatening allergic reactions. Such reactions may include low blood pressure and fainting, which indicate shock; swelling of the face, eyelids, tongue or throat; and asthma, wheezing, or other breathing problems. Patients who experience any of these reactions require immediate medical attention. Because of the small but serious threat that LHRH antagonists pose, their use is limited. Only patients with advanced, symptomatic prostate cancer who have no other treatment options or who refuse surgery can take them. Patients receive LHRH antagonists via injections into the muscles of the buttocks. To date, Plenaxis is the only LHRH analog approved for use in men with advanced prostate cancer. Other possible side effects include hot flashes, insomnia, pain, breast enlargement, breast pain or tenderness, back pain, constipation, or edema -- the buildup of fluids in the ankles and legs.
Antiandrogens for Prostate Cancer
These prostate cancer drugs work by blocking the effect of testosterone in the body. Antiandrogens are sometimes used in addition to orchiectomy or LHRH analogs.This is due to the fact that the other forms of hormone therapy remove about 90% of testosterone circulating in the body. Antiandrogens may help block the remaining 10% of circulating testosterone. Using antiandrogens with another form of hormone therapy is called combined androgen blockade (CAB), or total androgen ablation. Antiandrogens may also be used to combat the symptoms of flare (temporary rise in testosterone that occurs with the use of LHRH agonists). Some doctors prescribe antiandrogens alone rather than with orchiectomy or LHRH analogs. Available antiandrogens include abiraterone acetate (Zytiga), biclutamide (Casodex), enzalutamide (Xtandi), and nilutamide (Nilandron). Patients take antiandrogens as pills. Diarrhea is the primary side effect when antiandrogens are used as part of combination therapy. Less likely side effects include nausea, liver problems, and fatigue. When antiandrogens are used alone they may cause a reduction in sex drive and impotence.