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Radiation Treatment and Brachytherapy
Radiation therapy involves the use of high-energy rays or radioactive particles to kill prostate cancer cells.
Brachytherapy is the implantation of tiny radioactive seeds into the cancer tumor.
External beam radiation is the application of radiation to the cancer from outside the body via radioactive beams.
Radiation kills cancer cells by damaging their DNA and limiting their ability to reproduce.
Radiation is the 2nd-most commonly used treatment for prostate cancer, and is often recommended for older men and those who face higher risks from undergoing surgery. Rates of success are similar to those for surgery, but depend largely on the cancer’s stage.
External Beam Radiation
External beam radiation therapy or EBRT involves the use of high powered X-rays, delivered from outside the body. EBRT is often recommended for men with prostate cancer that has spread outside the prostate but remains confined to the immediate area.
This procedure is painless and only takes a few minutes, but needs to be done five days a week, for about seven or eight weeks.
The rays pass through and can damage other tissue on the way to the tumor, causing side effects such as short term bowel or bladder problems, and long term erectile dysfunction. Radiation therapy can also temporarily decrease energy levels and cause loss of appetite.
Imaging studies are done to determine, as precisely as possible, the location of the cancer before treatment.
New techniques are being developed in an attempt to lessen the damage to surrounding tissue.
3-dimensional conformal radiation therapy (3-D CRT) involves beams of radiation aimed from several different directions. The beams overlap at the location of the cancer, providing a higher dose of radiation while exposing the surrounding tissue to lower doses.
Digital imaging and computer software are used to precisely focus the radiation to the shape of the tumor. Researchers are also experimenting with higher doses of radiation to determine how much can be delivered without a significant increase in side effects.
Intensity modulated radiation therapy (IMRT) is an even more precise version of 3-D CRT in which many very small beams are used and the intensity of each can be precisely controlled to ‘bend’ around healthy tissue.
Proton beam radiation therapy uses proton beams, not X-rays. Proton beams deliver radioactive particles to kill the cells at the end of their path, leaving the tissue they passed through undamaged. This procedure requires the use of a particle accelerator, limiting its availability to a very few locations.
Internal Radiation
Internal radiation via seed implants, also known as Brachytherapy, involves the injection of tiny ‘seeds’ containing radioactive isotopes into the prostate.
The radiation only reaches a few millimeters from the seeds, so they can deliver a higher dose in a smaller area, causing less damage to the surrounding tissue. Brachytherapy is most often recommended for early prostate cancers confined to a limited area.
The seeds are smaller than a grain of rice, and the number used varies from 40-120, depending on the size of the area to be treated. The seeds are left in place permanently, and usually lose their radioactivity within a year. This procedure takes about 1-2 hours under anesthesia.
Internal radiation also causes side effects such as short term bowel or bladder problems, and long term erectile dysfunction. Internal radiation therapy can also temporarily decrease energy levels and cause loss of appetite.
High-dose-rate brachytherapy (HDR) is sometimes used for patients with more aggressive cancers. HDR involves very short term insertion of seeds with a higher dose of radiation, sometimes in conjunction with external radiation.
Side Effects
Long-term erectile dysfunction (ED) develops in 10-40% of men during the 2 years following external radiation (EBRT), and about 10-60% of men following internal or brachytherapy. These variations largely depend on the patient’s age. About 50% of men suffering from ED as a result of radiation treatment respond well to treatment with ED drugs.
Most men suffer some urinary problems during radiation treatment. These usually disappear within a few months. Only about 5% suffer severe or permanent symptoms. Temporary rectal problems occur for less than 10% of men, but it is normal to find some blood in the bowel after treatment.
Additional Uses for Radiation Therapy
External radiation therapy can be used as a follow-up or ‘salvage’ treatment for men who have signs of cancer recurrence following surgery or initial radiation treatment. In a study published in the Journal of the American Medical Association, on March 17, 2004, external radiation therapy eliminated remaining prostate cancer in 80% of surgery patients with post-surgery prostate cancer recurrence.
For treating pain associated with metastic prostate cancer, radioactive medications can be injected into the bloodstream to treat cancer in multiple bone areas. These are compounds of radioactive materials bound to calcium so as to be drawn into bone.
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