Wednesday, May 11, 2011

Prostate cancer and hormonal therapy

The prostate cancer develops most frequently in men over fifty. This cancer can occur only in men, as the prostate is exclusively of the male reproductive tract. It is one of the most common types of cancer in men. Many factors, including genetics and diet have been implicated in the development of prostate cancer. However, many men who develop prostate cancer never have symptoms, undergo no therapy.  

Prostate cancer is most often discovered by PSA or Prostate Specific Antigen screening and less commonly by physical examination or by symptoms. Suspected prostate cancer is typically confirmed by taking a biopsy of the prostate and examining it under a microscope. 

Some treatment options for prostate cancer with intent to cure are primarily surgery and radiation therapy. Other treatments such as hormonal therapy. Hormonal therapy uses medications or surgery to block prostate cancer cells from getting dihydrotestosterone (DHT), a hormone produced in the prostate and required for the growth and spread of most prostate cancer cells. Blocking DHT often causes prostate cancer to stop growing and even shrink. Hormonal therapy for prostate cancer targets the pathways the body uses to produce DHT. A feedback loop involving the testicles, the hypothalamus, and the pituitary, adrenal, and prostate glands controls the blood levels of DHT. 

First, low blood levels of DHT stimulate the hypothalamus to produce gonadotropin releasing hormone (GnRH).  GnRH then stimulates the pituitary gland to produce luteinizing hormone (LH), and LH stimulates the testicles to produce testosterone. Finally, testosterone from the testicles and dehydroepiandrosterone from the adrenal glands stimulate the prostate to produce more DHT. 

Hormonal therapy can decrease levels of DHT by interrupting this pathway at any point.  GnRH action can be interrupted in one of two ways. GnRH antagonists suppress the production of LH directly, while GnRH agonists suppress LH through the process of downregulation after an initial stimulation effect.  GnRH antagonist for example abarelix,  while the GnRH agonists include leuprolide, triptorelin, goserelin and buserelin. Initially, GnRH agonists increase the production of LH. However, because the constant supply of the medication does not match the body's natural production rhythm, production of both LH and GnRH decreases after a few weeks.
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