Prostate Cancer (cont.)

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Cryotherapy

Cryotherapy is most frequently used as a salvage treatment after failure of radiation therapy. As an outpatient, hollow needles are placed into the prostate through the perineum (the space between the scrotal sac and the anus) under image guidance. A gas is passed through the needles to freeze the prostate. Warm liquid is passed through the urethra at the same time to protect it. The needles are removed after the procedure. While potentially effective for local control of cancer in the prostate gland, the side effects can be significant and include pain and the inability to urinate. Potential long-term effects include tissue damage in needle-insertion areas, impotence, and incontinence. Cryotherapy is not an appropriate primary treatment for management of prostate cancer.

Hormonal therapy

Prostate cancer is highly sensitive to the level of the male hormone testosterone, which drives the growth of prostate cancer cells in all but the very high-grade or poorly-differentiated forms of prostate cancer. Testosterone belongs to a family of hormones called androgens, and today front-line hormonal therapy for prostate cancer is called androgen deprivation therapy (ADT).

Doctors can block the function of the testes in a controllable and REVERSIBLE fashion with drugs which affect the hormone system of the body and stop the main driver of the testes, the pituitary gland at the base of the brain, to stop stimulating the testes to make testosterone. These agents can result in shrinkage of the prostate gland, can stop prostate cancer cells from growing for up to many years, and can relieve pain caused by prostate cancer which has spread or metastasized into the bones.

Hormonal treatment today is primarily used in the treatment of locally advanced and metastatic prostate cancer. It can be combined with radiation therapy in attempts to cure prostate cancer. Its primary role is in the treatment of widespread or metastatic prostate cancer. While it is not a curative treatment in that setting, it can both reduce symptoms and prolong life.

Today medicines used to block testosterone production by the testes include:

  • LH-RH agonists: Leuprolide (Lupron), goserelin (Zoladex), histrelin (Supprelin LA), and triptorelin (Trelstar) are examples of these mediations. These are either given by injection into the muscle or under the skin at varying intervals of at least one month or longer.
  • LH-RH antagonists: Degarelix (Firmagon) is a monthly injection that is given under the skin.
  • Other drugs can block the effect of testosterone. These anti-androgen drugs include flutamide (Eulexin), bicalutamide (Casodex), nilutamide (Nilandron), and an even more effective form called enzalutamide (Vfend).

Both surgical and medical castration result in impotence. They also can cause hot flashes, fatigue, and thinning of the bones (osteoporosis) over time. They may be done individually or combined in what is called a combined androgen blockade. The combined blockade approach has not been proven to be more effective at this time than orchiectomy (removal of the testes) and is more expensive.

Other hormonal treatment options include:

  • Estrogen: This female hormone has been utilized in the treatment of prostate cancer. It's mechanism of action remains under study, and its association with a high risk of heart attack and blood clots when used in high doses has diminished the frequency of its use, particularly in front-line therapy. Estrogen and related drugs still play a role in the treatment of metastatic prostate cancer.
  • Adrenal androgen synthesis inhibitors: This group includes a drug called ketoconazole which was primarily developed to treat fungal infections. More recently an agent called abiraterone acetate (Zytiga) has been developed. It has a similar effect on androgen synthesis, but it is more powerful than ketoconazole (Nizoral) and has fewer side effects.
  • Steroids: These agents including prednisone may have beneficial hormonal effects in prostate cancer, including slowing the production of androgen by the adrenal glands. They often make the patient feel better, but have many side effects including inducing or worsening diabetes, fluid retention, cataract formation, weight gain, and osteoporosis.
  • Agents that block the conversion of testosterone to its active metabolite: Finasteride (Proscar) and dutasteride (Avodart) have been used in treating prostate cancer by preventing the conversion of testosterone to its active metabolite called DHT (dihydrotestosterone). These drugs are frequently utilized for the symptoms of prostate enlargement in men without prostate cancer, and appear to reduce the risk of development of prostate cancer. Their side effects are limited. They are used in combination with other agents to optimize androgen blockade.
Medically Reviewed by a Doctor on 9/4/2014

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