There are few options for treating painful bone metastasis in multiple sites. Hemibody irradiation, although effective, is limited due to the serious hematologic toxicity. Therefore, use of radiophamaceuticals has been attempted particularly for
the
osteoblastic bone metastasis. Strontium-89 (Sr-89) is a pure beta emitter with its energy 1.4 MeV. It follows the biochemical pathways of calcium and selectively concentrates at the metastatic bone sites with minimal hematologic toxicity.
From 1993 to 1994, Sr-89 treatment has been performed in 8 patients with painful bone metastasis from either prostate (6 patients) or breast cancers (2 patients). The patients had the initial level of WBC 3000/L, platelets 100,000/L, and normal
renal
function. Four mCi(148 MBq) of Sr-89 was intravenously injected and the patients were regularly followed with blood cell count test, simple bone x-ray, and radioisotpe bone scan.
The changes of subjective pain were scored in 6 patients until the time of this report. Excellent pain relief was achieved in all except 1 patient, who died 1 month after Sr-89 treatment due to advanced disease. Accordingly, the amount of the
analgesics
intake by the patients showed corresponding decrease.
There was slight decrease in the level of WBCs and plateletes at 2~6 weeks after Sr-89 treatment, however those soon recovered with conservative management.
Above results show that the Sr-89 treatment can provide effective palliation in patients with painful bone metastasis with acceptable toxicity. However, further study is urgent to establish its indication, timing, and combination with local
radiotherapy.
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