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Internal Radiation Therapy
Radiation can also be delivered to the prostate from dozens of tiny radioactive seeds implanted directly into the prostate gland. This approach, known as interstitial implantation or brachytherapy, has the advantage of delivering a high dose of radiation to tissues in the immediate area, while minimizing damage to healthy tissues, such as the rectum and bladder.
As practiced today, internal radiation therapy relies on ultrasound or CT (computed tomography) to guide the placement of thin-walled needles through the skin of the perineum. Seeds made of radioactive palladium or iodine are delivered through the needles into the prostate, according to a customized pattern -- using sophisticated computer programs -- to conform to the shape and size of each man's prostate.
The implantation procedure can be completed in an hour or two under local anesthesia; the patient typically goes home the same day.
The seeds emit radiation for several weeks, then remain permanently and harmlessly in place. Alternatively, some doctors use much more powerful radioactive seeds over a period of several days. Such temporary implants, which require hospitalization, may be combined with low doses of external beam radiation.
Because the experience with modern internal radiation therapy techniques is relatively recent and limited to carefully selected patients, long-term results are not yet known. At 5 years, more than 90 percent of patients remain free of disease.
Internal radiation therapy is not well suited for:
- Large or advanced tumors
- Men previously treated with transurethral resection of the prostate (TURP) for benign prostatic hyperplasia (BPH), who run an increased risk for urinary complications.
For men with small, well-differentiated tumors, it may provide an option that:
- Is less invasive
- Has fewer side effects
- Takes less time to perform
- Requires less time in the hospital
- Is less costly than either external radiation or surgery.
Possible Problems With Internal Radiation Therapy
Post-implant discomfort can usually be controlled by oral painkillers. The man can expect a few weeks of incontinence, but long-term complications, such as prostatitis or urinary incontinence, are uncommon and generally not severe. Sexual impotence occurs in about 15 percent of men under age 70 and in about 30 percent to 35 percent of men over age 70.