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Prostate Cancer (cont.)

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Radiation therapy

Radiation therapy involves potentially curative treatment using machines that generate and administer controlled, invisible beams of energy known as radiation. This is called external beam radiation therapy (EBRT). It also can be done using radioactive sources, or seeds, implanted permanently, or higher energy sources placed temporarily into the body. This technique is called brachytherapy.

An X-ray machine uses a low energy radiation beam to take a picture of a portion of the body. Radiation therapy machines put out high energy beams that can be focused very precisely to deliver treatment to a site. The radiation does not “burn out” the cancer, but damages the cells' DNA, which causes the cancer cells to die. This process can take some time to occur.

The radiation passes directly through the tissues in EBRT. Radiation treatment used today delivers very little energy to normal tissues. It just passes through. Most of the energy is delivered directly to the area of the prostate gland containing cancer. This process minimizes damage to healthy tissue.

EBRT can be administered in a variety of different ways including 3-D CRT, IMRT, and others. EBRT is classically administered in brief daily treatments, 5 days a week over several weeks. While the radiation does not remain in the body with this approach, the effect of the daily fractions is cumulative. Newer forms of EBRT using machines called CyberKnife may be completed in shorter periods of time.

Radiation therapy to the prostate gland by external beam technique may cause fatigue and bladder and/or rectal irritation. These effects are usually temporary but may recur or persist long after treatments are finished. Radiation damage to adjacent tissues can cause skin irritation, and local hair loss. Delayed onset of impotence can occur after radiation therapy due to its effect on normal tissues including nerves adjacent to the prostate. Radiation therapy may be given alone or in combination with hormonal therapy which can also shrink up the prostate gland thereby reducing the size of the radiation area or field that needs to be treated.

A recently popular technique of EBRT is called proton beam radiation, which can theoretically more closely focus on the area being treated. Proton beam radiation therapy is more expensive. Its side effects presently appear similar to those discussed for standard radiation therapy.

EBRT is appropriate for men who are candidates for radical prostatectomy but do not wish to undergo the surgery. It is also used to shrink tumors and reduce pain in areas where prostate cancer is damaging bone, or is pressing on important structures including the spinal cord.

Brachytherapy refers to the use of radiation sources -- sometimes referred to as seeds -- placed into the prostate gland. Brachytherapy may be done with what is called low-dose rate (LDR) technique. In LDR brachytherapy types of radioactive seeds, which only briefly put out a form of radiation which does not travel very far through tissues, are permanently implanted in the prostate gland. High-dose rate (HDR) brachytherapy involves the temporary placement of different types of seeds or sources which give off higher amounts of more penetrating radiation. These seeds administer higher doses of radiation for longer periods of time and cannot be left in the body. Such sources are placed in the prostate gland through surgically implanted tubes. These HDR sources are removed along with the tubes in a couple of days. In LDR brachytherapy, the seeds are placed in the operating room using image guidance to ensure the seeds go into the right places; 40 to 100 seeds may be placed. With LDR, you can go home shortly after you wake up after the procedure. In HDR, you must stay at the hospital for a few days. If the prostate gland is large, hormonal treatment may be used to shrink the gland before the brachytherapy is done. Brachytherapy may also be combined with external beam radiation therapy to further increase the dose of radiation therapy given to the prostate gland.

Brachytherapy can cause some blood in the urine or semen. It can cause a feeling similar to constipation due to the swelling of the prostate gland. It can also make you feel that you want to move your bowels more often. There may be some long-term problems with irritation of the rectum, difficulty urinating due to scar tissue formation, and even delayed-onset impotence.

Brachytherapy is appropriate for men with tumors staged T1 to T3 with PSA less than 20. It is not appropriate if you have had a prior procedure -- transurethral prostatectomy (TURP) -- which removes part of the prostate in cases of benign prostatic hypertrophy (BPH).

Note: Radiation therapy can be performed if prostate cancer recurs in the region where the prostate was, and can potentially cure a locally recurrent prostate cancer if it has not spread beyond the area.

If radiation fails to control the cancer, surgery is difficult -- if not impossible -- to perform due to scar tissue which develops in the area.

Medically Reviewed by a Doctor on 9/4/2014

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Source: MedicineNet.com
http://www.medicinenet.com/prostate_cancer/article.htm

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