Hormone therapy, also known as androgen deprivation therapy (ADT) or androgen suppression therapy, is a treatment for prostate cancer that aims to reduce or block the action of male hormones (androgens), particularly testosterone, which can stimulate the growth of prostate cancer cells. Here’s how it works:

Mechanisms of Hormone Therapy

1. Reducing Androgen Production
   • Luteinizing Hormone-Releasing Hormone (LHRH) Agonists: These drugs lower testosterone levels by stopping the testicles from producing testosterone. Examples include leuprolide (Lupron), goserelin (Zoladex), and triptorelin (Trelstar).
     • Initial Surge: Initially, LHRH agonists can cause a temporary increase in testosterone levels before they drop significantly. This is known as the "flare" effect.
   • LHRH Antagonists: These drugs, such as degarelix (Firmagon), reduce testosterone levels more quickly and without the initial surge seen with LHRH agonists.
     • Sources: American Cancer Society, National Cancer Institute
2. Blocking Androgen Action
   • Anti-Androgens: These medications block the action of androgens by attaching to androgen receptors on prostate cancer cells. Examples include bicalutamide (Casodex), flutamide (Eulexin), and enzalutamide (Xtandi).
     • Combination Therapy: Often used in combination with LHRH agonists or orchiectomy to provide more complete androgen blockade.
   • Sources: Mayo Clinic, American Cancer Society
3. Surgical Removal of Testicles (Orchiectomy)
   • Description: A surgical procedure to remove the testicles, which are the primary source of testosterone production.
   • Effectiveness: This method provides an immediate and significant reduction in testosterone levels.
   • Sources: National Cancer Institute, American Cancer Society

Types of Hormone Therapy

1. LHRH Agonists and Antagonists
   • LHRH Agonists: Leuprolide (Lupron), goserelin (Zoladex), triptorelin (Trelstar), histrelin (Vantas).
   • LHRH Antagonists: Degarelix (Firmagon), relugolix (Orgovyx).
   • Mechanism: Lower testosterone levels by signaling the pituitary gland to stop stimulating testosterone production in the testicles.
   • Sources: American Cancer Society, National Cancer Institute
2. Anti-Androgens
   • Examples: Bicalutamide (Casodex), flutamide (Eulexin), nilutamide (Nilandron), enzalutamide (Xtandi).
   • Mechanism: Block androgen receptors on prostate cancer cells, preventing testosterone from stimulating cancer growth.
   • Sources: American Cancer Society, Mayo Clinic
3. Other Hormone Therapies
   • CYP17 Inhibitors: Abiraterone (Zytiga) blocks an enzyme involved in testosterone production, reducing androgen levels from all sources.
   • Estrogens: Less commonly used today due to cardiovascular side effects, estrogens can also reduce testosterone levels.
   • Sources: American Cancer Society, National Cancer Institute

Side Effects of Hormone Therapy

• Hot Flashes
• Loss of Libido and Erectile Dysfunction
• Osteoporosis
• Weight Gain
• Loss of Muscle Mass
• Fatigue
• Mood Changes and Depression
• Increased Risk of Cardiovascular Disease

Management: Side effects can often be managed with lifestyle changes, medications, and other treatments. Patients should discuss potential side effects and their management with their healthcare provider.

Sources for Further Reading

• American Cancer Society: Hormone Therapy for Prostate Cancer
• National Cancer Institute: Prostate Cancer Treatment (PDQ®)–Patient Version
• Mayo Clinic: Prostate Cancer Treatment

These sources provide comprehensive information about how hormone therapy works for prostate cancer and its various aspects, including mechanisms, types, and potential side effects.