Radioactive seed implants (brachytherapy)

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Radioactive seed implants, also called brachytherapy, are a newer method of radiation treatment that delivers radiation internally by implanting small radioactive pellets directly into the prostate. The radioactive seeds are implanted either temporarily or permanently. The permanent form of implantation is most commonly used.

Radioactive seed implants are injected directly into the prostate and are being used more frequently as a treatment for prostate cancer. This method delivers a higher dose of radiation than does external beam radiation, but it treats a smaller area.

About the radioactive seed implant procedure

The procedure to implant radioactive seeds typically lasts one to two hours and is done on an outpatient basis while you're under spinal or general anesthesia.

Your doctor injects between 80 and 120 rice-sized radioactive seeds into your prostate. The exact number of seeds used depends on the size of the prostate. Seeds are inserted through hollow needles that pass through the skin between your scrotum and anus (perineum).

An ultrasound probe inserted into your rectum guides the doctor in placing the seeds. A template attached to the outside of the probe and held against your perineum guides and steadies the needle loaded with seeds.

The procedure is generally easier to perform on smaller or moderate-sized prostates, but men with larger prostates also may be considered for this treatment. Some men with very large prostate glands or a narrow pelvis are first given hormone injections to shrink the prostate to allow implantation.

The seeds may contain one of several radioactive isotopes — including iodine or palladium. These seeds:

Usually remain in place permanently, even after they stop emitting radiation
Generally emit radiation that extends only a few millimeters beyond their location, and isn't likely to escape your prostate area
Lose all radiation inside the pellets within a year

It's recommended that you avoid prolonged close contact with children and pregnant women for the first few months after implantation. However, several studies have demonstrated that spouses of men with seed implants received no additional radiation beyond that which normally is present in the environment.

Side effects of radioactive seed implant therapy
Side effects of radioactive seed implant therapy include sexual, urinary and rectal problems, appetite loss, and fatigue. Some side effects are long term, and others, such as fatigue and appetite loss, usually go away a couple of months after treatment. The long-term effects of radioactive seed implants are still evolving.

Sexual function. Radioactive seed implant therapy can affect your sexual function the same as can external radiation. Most men don't have problems with erections or intercourse immediately after seed implantation. However, long-term effects can damage nerves that control erections and arteries that carry blood to the penis. One-third to one-half of men who undergo seed implantation therapy for early-stage prostate cancer may develop erectile dysfunction or impotence as a complication of treatment. The younger you are at the time of treatment, the better your chance of retaining normal sexual function. Oral medications, penile injections or insertion of medications into the urethra, and vacuum pumps can, in most cases, help maintain an active sex life after treatment.
Urinary problems. Seed implants deliver a high dose of radiation to your urethra, causing most men to have urinary problems during treatment. The most common urinary problems are constantly feeling as if you have to urinate, burning or pain while urinating, frequent urination and urine leakage. Most of these problems are temporary and gradually get better in a few months after completing treatment. You may need medication to treat these symptoms, and some men need to use self-catheterization to help them urinate. A few men have severe and sometimes permanent symptoms. Urinary symptoms tend to be worse and last longer with seed implants than with external beam radiation.
Rectal problems. Rectal problems — including diarrhea, rectal bleeding, rectal urgency (a sense that you have to have a bowel movement) and discomfort during bowel movements — develop infrequently after seed implantation. Severe rectal symptoms can occur if the seeds are implanted too close to the rectum or if a large number of seeds are needed in the prostate gland near the rectum because of a large volume of tumor in this location. Men usually have fewer rectal complications with radiation seed implants than they do with external radiation.
Other side effects. Seed implantation therapy rarely causes fatigue and loss of appetite. With radioactive seed implants, there is a small risk that the seeds could move into the lungs through the bloodstream, but any damage or side effects are not a problem.
Late effects. Some men develop new side effects several years after finishing radiation therapy. Side effects such as urinary incontinence and sexual dysfunction can occur with either external beam radiation or radioactive seed implants, although those treated with radioactive seed implants have more severe symptoms.