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Published on Sep 14, 2010
Nearly half of all cancer patients receive radiation therapy to treat their cancer or relieve symptoms. Radiation therapy kills cancer cells by destroying their DNA, but it may also affect normal cells and adjacent organs in the process. The goal of brachytherapy, or internal radiation therapy, is to precisely target the radiation exposure to the tumor where it is needed and avoid surrounding healthy tissues by placing radioactive sources directly on or inside cancer tissues.
"By treating the tumor from the inside out, we can rapidly deliver higher doses of radiation to the tumor, with relatively few side effects," explains UCLA radiation oncologist and chief of the Division of Brachytherapy D. Jeffrey Demanes, M.D., a pioneer of high-dose-rate (HDR) brachytherapy. HDR brachytherapy has been used successfully to treat prostate, breast, head and neck, gynecologic, gastrointestinal, skin, softtissue sarcomas and many other types of cancer. "In some cases it is used as the only treatment, and in other cases this precision radiation therapy is combined with surgery, external-beam radiation therapy or chemotherapy, depending upon the type and extent of the cancer and needs of the individual patient," Dr. Demanes says.
HDR brachytherapy uses a computerized robotic-delivery device to temporarily insert a tiny radiation source into a tumor. It is performed by inserting thin, straw-like applicators about the size of an intravenous line in or near the treatment site. Once the applicator has been optimally positioned, the physicians and highly trained physics team work with a treatment-planning computer program to create a virtual image of the implant and surrounding anatomy so they can customize a precise, patientspecific dose distribution. Electronic instructions for positioning the miniature radioactive source are then sent to a robotic "afterloader," which is operated by a specially trained radiation therapist to deliver the radiation source.
Unlike older forms of brachytherapy, which leave radioactive seeds in or near the cancer site for an extended period of time while the patient is hospitalized, HDR brachytherapy can often be done on an outpatient basis in a specially designed treatment booth. The HDR applicators and radioactive material are completely removed so there is no residual radiation or radioactivity after treatment. The entire HDR treatment process is typically completed in one to two weeks.
"HDR brachytherapy tends to have an excellent risk-benefit ratio," Dr. Demanes says. "In addition to being highly effective, it's a relatively painless procedure, with fast recovery and the acute side effects tend to be of short duration. It allows patients to get back to their normal lives more quickly than other kinds of radiation therapy."
When used as a primary treatment, HDR brachytherapy is designed to preserve the structure and function of the involved organs. It can also extend the effectiveness of cancer surgery by killing cancer cells at the surgical margins, and it can be used where other forms of radiation have been previously applied and are no longer considered advisable.