Bone pain palliation with Strontium-89 in cancer patients with bone metastases

Strontium-89 is a pure beta -emitting radioisotope, a chemical analogue of calcium, and it is therefore avidly concentrated by areas of high osteoblas tic activity. Selective uptake and prolonged retention at sites of increase d bone mineral turnover provide precise bone lesions targeting. Sr-89 chlor ide (commercialised as Metastron((R))) is typically administered in a singl e 150 MBq parenteral dose. Its radioactive emission poses very Little radio protection concerns. Overall, studies show pain relief in up to 80% of pati ents, of which 10 to 40% became effectively pain free. The mean duration of palliation was 34 months. The mechanism of pain relief is controversial; i t is probably, but not only, related to the absorbed dose in the tumour and bone. There is no clear dose-response relationship. The only reported toxi city is temporary myelosuppression. WBC and platelets should be monitored a t least on a weekly basis until they return to baseline. It seems that only patients with a reasonably good general condition stand to benefit from th is treatment. In conclusion, systemic radionuclide therapy using Sr-89 repr esents a feasible, safe, effective, well tolerated and cost-effective palli ative treatment in;patients with refractory bone pain.