Initial study of single-dose HDR brachytherapy for localized prostate cancer

In the past, high-dose-rate (HDR) brachytherapy has been used alone or (more commonly) in combination with external beam radiation therapy (EBRT) for the treatment of localized prostate cancer. However, when used alone, it has been necessary to treat the patient with several sessions of HDR brachytherapy. Clinicians at Beaumont Hospital in Detroit, Michigan, have now initiated a study of single-dose HDR brachytherapy in the treatment of men with low- and intermediate-risk, localized prostate cancer (clinical stage T1c through T2b tumors, a Gleason score of 6 or 7, and a PSA level > 15 ng/ml). However, this clinical study does not (at least yet) appear to be listed on the web site.

Brachytherapy has historically been available in two basic types: using permanent radioactive seeds that are implanted in the prostate and left there or using HDR brachytherapy in which the radioactive source is implanted temporarily into the prostate, usually for a period of only minutes. However, because HDR brachytherapy has required the patient to be treated over two to 10 sessions, it has been much less commonly employed than permanent seed implantation, which can be carried out in a single outpatient procedure.

According to the news story on the Beaumont Hospital web site, Martinez and his colleagues have now treated their first four patients with single-dose HDR brachytherapy, employing iridium-192 as the radiation source. They claim that — using this technique — they are able to deliver more radiation to the prostate, to increase the likelihood of effectively killing the cancer cells present, and to minimize radiation exposure to surrounding tissues. Obviously, since no radioactive material is left in the patient’s body, there is no risk of radiation exposure for others who may come close to the patient for extended periods of time.

If single-dose, outpatient HDR brachytherapy can be shown to have the same quality of outcome as single-day, outpatient permanent seed brachytherapy, one can reasonably expect the popularity of this technique to increase. However, it may be a while before we have sufficient data to really know whether the long-term outcomes and side effects are comparable to those achieved with permanent seed brachytherapy.

The new, single-dose HDR brachytherapy procedure takes about 3 hours, from the time initial spinal anesthesia is administered. Plastic needles are placed into the prostate using ultrasound guidance. Each needle is then loaded with a single radiation seed, and the seeds are gradually moved through the needles by a fine cable controlled by computerized equipment. Actual treatment with the temporarily implanted radiation sources takes only 15 minutes.

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