Radiation
This treatment kills cancer cells either through external beam radiation therapy, by implanting tiny radioactive seeds through brachytherapy, or by radiosurgery.
External Beam Radiation Therapy
External beam radiation therapy, or EBRT, is delivered by a high powered X-ray machine. EBRT is often recommended for men with prostate cancer that has spread outside the prostate, but still 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 X-rays pass through and can damage other tissues on the way to the tumor, however, causing side effects such as short-term bowel or bladder problems, and long-term erectile dysfunction. Radiation therapy can also temporarily decrease one’s energy level and cause loss of appetite.
Imaging studies are taken 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. Three-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. As this procedure requires the use of a particle accelerator, the availability of proton beam radiation therapy is limited.
Brachytherapy
Radiation therapy involves the use of high-energy rays or radioactive particles to kill prostate cancer cells. Brachytherapy (internal radiation) is the implantation of tiny radioactive seeds into the cancer tumor.
Radiation kills cancer cells by damaging their DNA and limiting their ability to reproduce. Radiation is the second most commonly-used treatment for prostate cancer; it is often recommended for older men and those who face a higher risk for undergoing surgery. Rates of success are similar to those for surgery, but depend largely on the cancer’s stage.
Internal radiation, through a procedure called 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, yet usually lose their radioactivity within a year. This procedure takes about one to two 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 one’s energy level and cause loss of appetite.
High-dose-rate brachytherapy (HDR) is sometimes used for patients with more aggressive prostate cancer. HDR involves a very short-term insertion of seeds with a higher dose of radiation and is sometimes in conjunction with external radiation.
Radiosurgery
Radiosurgery is a medical procedure that has been used to treat patients with brain tumors or other kinds of cancer, including prostate cancer. The procedure, which is non-invasive as no cutting is involved, directs beams of ionizing radiation to the prostate.
Radiosurgery is primarily used for the therapy of tumors, vascular lesions and functional disorders. Significant clinical judgment should be used with this technique, with considerations that include lesion type and size, and age and general health of the patient. Radiosurgery is not recommended for excessively large tumors or tumors too numerous for practical treatment.
Radiosurgery can be especially helpful for patients in poor health and those with tumors which cannot be treated by other therapies. However, the outcome of radiosurgery may not be evident for months after the treatment.
Since radiosurgery does not remove the tumor, but results in a biological inactivation of the tumor, lack of growth of the tumor is typically considered to be treatment success.
