'Hot Shot' Beats Back Prostate Cancer Metastases
WebMD News Archive
Feb. 2, 2001 -- A single dose of the radioactive drug strontium-89 (Sr-89) can help some prostate cancer patients live longer, researchers from the University of Texas M.D. Anderson Cancer Center report in the Feb. 3 issue of The Lancet. Sr-89 has long been used to relieve the pain of metastatic prostate cancer. This is the first study to show that it also can slow the advance of the disease.
A team led by Shi-Ming Tu, MD, studied the effects of Sr-89 in patients who had advanced prostate cancer but whose cancer had either stabilized or improved after treatment with standard chemotherapy. Following the first cycles of chemotherapy, the patients were treated either with doxorubicin (Adriamycin) or with doxorubicin plus a single dose of Sr-89.
Co-author Ebrahim Delpassand, MD, tells WebMD that adding the single dose of Sr-89 increased the amount of time it took for the prostate cancer to progress and also increased the patients' average survival time.
However, he warns that this was a small study, with only 103 patients, and that its results must be confirmed in more patients before final conclusions can be drawn. His group has launched a larger study and expects to complete it by the end of this year.
"An additional advantage of this combination is that it can be given entirely as an outpatient treatment," says Delpassand, who is chief of clinical nuclear medicine at the University of Texas M.D. Anderson Cancer Center. "If the larger study confirms the benefits seen in the smaller trial, there is no reason this combination could not be used in ordinary community hospital clinics, although it does require a physician who has the special license necessary for giving radioactive drugs to patients."
Delpassand tells WebMD that the M.D. Anderson team developed the pilot study after noticing that prostate cancer patients treated with repeated doses of Sr-89 to relieve pain appeared to sometimes live longer than patients who didn't receive the drug. Sr-89 "hones in" on bone cells that also are targets of prostate cancer when it spreads, and this suggested that it also might have a "tumor killing" effect.
"Most drugs target cancer metastases that spread into soft tissue, but Sr-89 is very specific for bone in delivering its radiation. That may mean that the combination of chemotherapy plus radiation from Sr-89 delivered to these target bone cells might be more effective than chemotherapy alone," Delpassand says.
According to Seymour H. Levitt, MD, adding Sr-89 to the regular chemotherapy regimen did not significantly increase its toxicity -- an important point when considering the patients who would be likely to receive this therapy. "In this situation, you are not likely to cure cancer. What you want is to relieve pain and to enhance the patient's quality of life," says Levitt, who is a professor of medicine in the department of therapeutic radiology-radiation oncology at the University of Minnesota Medical School in Minneapolis. Levitt, an expert on palliative treatment of bony metastases, was not involved in the M.D. Anderson study.