Radiation therapy uses very high-energy rays to kill prostate cancer cells, shrink tumors or to prevent cancer cells from dividing and spreading. In early stages of prostate cancer, radiation therapy may cure the disease. Radiation therapy also may be used alone or in combination with hormone therapy. There are two ways in which the high-energy rays can be delivered. External beam radiation or a type of internal radiation called radioactive seed implantation also known as brachytherapy.
Seed Implantation | External Beam Radiation | IMRT | Disadvantages
Seed Implantation (interstitial radiation therapy or brachytherapy)
Radiation is given off by tiny seeds, which are placed directly into the prostate. Brachytherapy may be used by itself or in combination with external radiation therapy. The seeds are too small to be felt by the patient and do not cause any discomfort. They are inserted into the prostate during a day surgery procedure after the patient is sedated using a local or general anesthetic. Specialized equipment like CT scans, ultrasound, and MRI help the surgeon and validation oncologist to place the seeds accurately. The seeds give off radiation continuously for weeks, months or up to a year and can remain safely in place for the rest of a person’s life. The amount of time the seeds remain radioactive depends on the dose and what type of radioactive material used.
By using brachytherapy, radiation is placed as close as possible to the cancerous cells, which receive the prescribed dose while surrounding normal tissue are relatively spared. Because it is designed to target the cancerous cells and not harm the surrounding area, brachytherapy is rarely recommended when the cancer has spread beyond the prostate gland.
External Beam Radiation Therapy
A non-invasive, non surgical treatment in which a machine delivers high energy x-rays, in brief daily treatments once per day Monday through Friday for several weeks. Many patients compare the treatments to having an x-ray. The procedure is painless and lasts for just a few minutes. External beam radiation therapy may be given alone or in combination with hormone therapy. Recent advances in radiation therapy have led to more sophisticated method of treatment called 3 dimensional conformal radiation therapy (3D-CRT). At the planning, a mold is made out of a moldable plastic or inflatable Styrofoam to help the patient keep still for treatment and be placed in the same position each day. After the mold is made, a CT scan is taken of the position so that the exact location of the prostate, bladder and rectum in the treatment position is identified. Computerized planning by a medical physicist and the radiation oncologist, choose the treatment angles that will best treat the prostate while minimizing dose to the bladder and rectum. Customized shielding is also designed to provide additional protection of the bladder and rectum.
Intensity modulated radiation therapy (IMRT)
The newest form and most sophisticated form of external beam radiation therapy, is an extension of 3D conformed radiation therapy. The software creates a treatment plan where the dose limitations are given for the bladder and rectum (most important near by normal tissue) while delivering the desired dose to the tumor. Limits to the normal tissue are accomplished using customized shielding that can continuously move during the treatment (dynamic multileaf collimator). This sophisticated customized shielding allows higher doses to be delivered to the tumor (prostate) potentially translating into increased chances of cure with acceptable side effects.
Disadvantages of Radiation Therapy
Radiation therapy can cause a variety of side effects. Most of these are minor and disappear after therapy stops. These side effects include tiredness, skin reactions in the treated areas, frequent and uncomfortable urination, and rectal irritation or bleeding. There is a chance of some permanent side effects. Bowel function may not completely return to normal even after treatment is complete. Development of impotence may occur up to 2 years later in a small percentage of patients.
External beam therapy is inconvenient in that it requires several weeks of brief daily visits to the radiation department.
Surgery | Prognostic Indicators | Therapy for Localized Prostate Cancer | Treatment of Metastatic Prostate Cancer