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Prostate Cancer (cont.)

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Radiation therapy

Radiation therapy as with surgical therapy is a potentially curative treatment that uses radiation to kill cancer cells. Radiation therapy can be performed via external beam therapy (EBRT) or the placement of radioactive seeds into the prostate (prostate brachytherapy).

EBRT

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 after the radiation treatments have been given.

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 able to be focused and 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 allow the treatment to be completed in shorter periods of time.

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. Studies comparing the effectiveness and overall results of conventional radiation therapy versus proton beam therapy have not been completed yet.

Radiation therapy to the prostate gland by external beam technique may cause fatigue and bladder and/or rectal irritation. One may experience frequency of urination or stools and blood in the urine or stools. 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. The NCCN guidelines recommend that patients with high-risk and very-high-risk prostate cancer receive neoadjuvant/concomitant/adjuvant hormone therapy (androgen deprivation therapy [ADT]) for a total of two to three years if the overall health of the patient permits and that patients with intermediate-risk prostate cancer be considered for four to six months of neoadjuvant/concomitant/adjuvant hormone therapy (ADT).

EBRT is appropriate for men who are candidates for radical prostatectomy but do not wish to undergo the surgery or who are not ideal surgical candidates.

EBRT may also be used to treat recurrent prostate cancer localized to the prostate bed (where the prostate was before it was removed surgically). It is also used to treat bone metastases (spread of the prostate cancer to the bone) to reduce pain or if the cancer 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) or high-dose rated (HDR) technique. In LDR brachytherapy, types of radioactive seeds, which only briefly put out a form of radiation that 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 that 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 -- 40-100 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 (ADT) 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. One can also experience transient troubles urinating, called urinary retention, related to swelling of the prostate gland, that may require short-term catheter placement. 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, low and intermediate risk tumors. Patients with a very large prostate or very small prostate, those with symptoms of bladder outlet obstruction, or who have had a previous transurethral resection of the prostate (TURP) are more difficult to treat and have a greater risk of side effects.

Brachytherapy can be used as a salvage therapy for recurrent/persistent prostate cancer after external beam radiation therapy (EBRT). The risk of side effects is increased when used as a salvage therapy.

Medically Reviewed by a Doctor on 11/9/2016

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

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