Myelotoxicity of samarium Sm 153 lexidronam in patients receiving prior treatment with chemotherapy or radiotherapy.

BACKGROUND The effect of prior treatment with radiotherapy and/or chemotherapy on the myelotoxicity of samarium lexidronam (Sm 153) in patients with metastatic bone lesions and bone pain was described. METHODS Single-institution retrospective chart review of patients receiving Sm 153. The effect of Sm 153 on peripheral white blood cell (WBC), platelet counts, and change from baseline was calculated. RESULTS The available hematologic data from records of 58 patients receiving 100 treatments with Sm 153 were reviewed. Prior treatment with radiotherapy or chemotherapy had no effect on changes from baseline or median nadir counts for either WBC or platelets when compared with patients not having such prior treatments. Multiple treatments with Sm 153 had no effect on change from baseline in WBC or platelet counts as compared with the initial administration. Median survival following the first dose of Sm 153 was 15 months. CONCLUSIONS Prior treatment with radiotherapy or chemotherapy did not affect the rates of myelotoxicity. Multiple treatments with samarium Sm 153 lexidronam also had no effect on severity of myelotoxicity with successive courses. Patients with bone predominant metastatic disease may survive for extended periods of time and may safely be treated with multiple modalities of therapy.