Strontium-89- safe for superscans and still safe and satisfying second time around

Full text: There remains a reluctance on both the part of referring and treating clinicians to use Sr-89 in patients with malignant 'superscan' appearances on bone scan or more than once because of perceptions regarding potential myelo-toxicity. We have therefore reviewed our experience with Sr-89 in 155 consecutive patients classified by extent of bone scan abnormality into groups with limited (<20 lesions, n = 20), extensive (>20 discrete lesions, n = 112) and (diffuse axial ± skeletal involvement, n =23) and assessed myelotoxicity at 1 month post-treatment. Results of myelotoxicity and efficacy were also assessed in 34 patients receiving a second dose of Sr-89 after a good response to their initial treatment course. For initial treatments, the median reduction in platelet counts for limited, extensive and superscans patients were 20%, 28% and 32% respectively (p= NS). No patients with superscan developed >grade 1 platelet toxicity whereas 8% of patients with extensive disease developed grade 2 or 3 thrombocytopaenia. Amongst 34 patients receiving a second course of treatment the median reduction in counts for patients with limited (n = 4), extensive (n=20) and superscan (n = 8) patients were 18%, 18%, and 33% respectively (p = 0.045). Two patients developed grade 3 thrombocytopaenia but both had reduced baseline platelet counts. No complications or platelet transfusions were recorded. Encouragingly the response rate with second administrations was 83% with no significant difference based on extent of disease. Our experience suggests that Sr-89 therapy is safe, even in patients with superscan appearances. There appears to be a slightly higher risk of myelotoxicity in patients with a superscan with second doses of Sr-89 but this is offset by reliable pain relief in patients with a previously favourable response to treatment. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc