MIAMI BEACH--Cancer patients treated with strontium-89 (Metastron) for palliation of their metastatic bone pain may also benefit therapeutically, said Michael J. Katin, MD, a radiation oncologist in Fort Myers, Florida, whose practice includes a significant number of patients with painful bone metastases resulting primarily from prostate cancer.
"Evidence is mounting to suggest that strontium-89 may retard the progression of metastatic disease," Dr. Katin said at a symposium on metastatic prostate cancer held in conjunction with the American Society for Therapeutic Radiology and Oncology (ASTRO) meeting.
Dr. Katin described the Trans-Canada Study, which tested the efficacy of strontium-89 adjuvant to local field external beam radiotherapy in 126 patients with multiple bone mets secondary to hormone-refractory prostate cancer.
Patients treated with strontium-89 had a larger decrease in new sites of pain, and significantly more of these patients reported no newly painful sites, compared with the placebo arm (59% vs 34% for the two groups, respectively). Blood levels of serum tumor markers were also significantly reduced in patients who received strontium-89, compared with placebo-treated patients, during the first 4 months after therapy.
Similar results were seen with the UK Metastron Investigators' Group study, which compared strontium-89 treatment with external beam therapy in 305 patients with painful prostatic metastatic cancer. Significantly fewer patients who received strontium-89 developed new painful sites or needed additional therapy than did those treated with radiation.
Since 1988, Dr. Katin has used strontium-89 in 229 patients. Overall, 76% had metastatic prostate cancer. Of these, pain decreased in 83% who were treated with a 50 µCi/kg injection; 13% had total relief of their pain and were able to discontinue their analgesics.
Dr. Katin emphasized that while he has not systematically examined the question of whether strontium-89 provides therapeutic benefit, he is nonetheless convinced that it has this property.