STRONTIUM-89 THERAPY FOR THE PALLIATION OF PAIN DUE TO OSSEOUS METASTASES

Objective.-To present the current state of systemic radiopharmaceutica l therapy for the palliation of pain in individuals with metastatic ca ncer and to evaluate the palliative effect and degree of hemotoxicity of strontium chloride 89 (Sr-89) in patients with painful osteoblastic metastases primarily from prostate and breast cancer. Data Sources an d Study Selection.-A MEDLINE search through December 1994 was performe d to identify English-language studies that met the following criteria . All eligible studies reported treatment of patients with painful ost eoblastic bony metastases primarily from prostate or breast cancer tre ated with intravenous Sr-89. For study eligibility, evaluation of clin ical response as assessed by the Karnofsky index, need for pain medica tion, or changes in mobility or sleep patterns was required. Hemotoxic ity data were a requirement. A minimum of 10 prostate cancer cases was necessary for study inclusion. Only those studies assessing clinical response following one injection of Sr-89 were included. Preliminary r eports of cooperative studies were not included. Doses of Sr-89 ranged from 0.6 MBq/kg (16 mu Ci/kg) to 400 MBq (10.8 mCi) per patient. Eval uation of patients for at least 3 months following Sr-89 treatment was required. In addition, two studies examining issues of cost with rega rd to Sr-89 treatment were identified. Data Extraction.-Baseline pain assessment and periodic pain estimates as measured by the Karnofsky in dex, medication diaries, changes in mobility, sleep patterns, and/or a bility to work were the basis for assessment of response. Baseline and periodic complete blood cell counts were the basis for hemotoxicity e valuation. Data Synthesis.-Palliation and hemotoxicity data were analy zed separately for each study. Some improvement occurred in as many as approximately 80% of patients. Several studies demonstrated complete relief of pain in at least 10% of patients. The nadir of platelet and white blood cell counts appears at approximately 4 to 8 weeks followin g injection, with a partial return to baseline by 12 weeks. As many as 10 injections spaced 3 months apart have been given to some patients with repeated palliative effect and without serious hemotoxicity. Rein jection may be limited by a platelet count below 60x10(9)/L, a white b lood cell count below 2.4x10(9)/L, or the absence of osteoblastic skel etal metastasis as seen on bone scan. Studies examining treatment cost s suggest that Sr-89 may decrease costs associated with palliation of pain due to metastatic disease. Conclusions.-As many as 80% of selecte d patients with painful osteoblastic bony metastases from prostate or breast cancer may experience some pain relief following Sr-89 administ ration. In addition, as many as 10% or more may become pain free. Dura tion of clinical response may average 3 to 6 months in some cases. Hem otoxicity is mild. A decrease in treatment costs with administration o f Sr-89 to patients with painful osteoblastic bony metastases from pro state cancer may occur. These observations reflect the preliminary nat ure of knowledge in this field and point to the need for larger clinic al trials of the use of Sr-89 palliation.