Intervertebral administration of 153Samarium with kyphoplasty for vertebral metastases

Abstract

13136 Background: Kyphoplasty is an effective procedure to alleviate pain in metastatic vertebrae. 153Samarium-EDTMP (153Sm) is used for palliative treatment of multiple bone metastases. The hematological toxicity is the main limiting factor. Objectives: Study the feasibility of intervertebral administration of 153 SM with Kyphoplasty. Assess procedure related morbidities specifically haematological since a direct vertebral route is planned though to a much smaller dose. Methods: IRB approval for an off label use of 153Sm-EDTMP was obtained. Six patients with documented vertebral bone metastasis and pathological compression fractures were studied (Thoracic in 2 and lumbar in 4). Primary cancer was lung in 2, prostate (1), maxillary sinus (1), myeloma (1) and colon (1). Serial dilution of 153 SM was performed to obtain 2 mci/1ml. Kyphoplasty procedure was carried out using the known protocol. 2 mCi of 153Sm was admixed with the bone cement and administered under tight radiation safety measures. Serial nuclear body scans were obtained. Pain assessment was evaluated using analog pain score at 1, 7 and 30 days. Serial blood counts are followed. Results: All patients tolerated procedure well. No immediate procedure(s) related morbidities were noted. One case was not technically satisfactory and no significant uptake was detected in the injected vertebra. Nuclear scan done on 0 revealed excellent radiotracer uptake in the other 5 vertebrae injected. The absorbed radiotracer was seen to target other skeletal metastatic lesions in 2 patients. There was no significant change in WBC, HCT or Platelets seen in blood counts obtained over one month post-procedure. Except for the first patient, no appreciable radiation leakage was encountered. Pain score was reduced from a mean of 8.5 to 3.2 during the first week and was maintained below score of 4 at one month assessment. Conclusions: The combination of intervertebral administration of 153SM and Kyphoplasty seems to be well tolerated. No haematological side effects were encountered; probably due to the use of only 2 mci compared to over 70 mci in intravenous administration. Pain control seems to be satisfactory at areas treated. Analysis of procedure related radiological changes is underway. No significant financial relationships to disclose.