Utility of bone marrow aspiration and biopsy in initial staging of Ewing sarcoma.

Abstract

The current standard of care for initial staging of pediatric Ewing sarcoma (EWS) patients is to obtain a bilateral bone marrow aspiration and biopsy (BMAB). The incidence of bone marrow (BM) disease in patients deemed non-metastatic by conventional and metabolic imaging and the concordance of BM positivity with other clinical characteristics are not well established. This study is a multi-institutional retrospective review of newly diagnosed EWS patients less than 40 years of age with initial staging that included imaging and BMAB. A total of 116 patients were eligible with 85 patients considered non-metastatic and 31 considered metastatic by imaging. None of the 85 patients with non-metastatic disease were BMAB positive (0%; 95% CI: 0-4.2%); 13 of the 31 patients with metastases were BMAB positive (41.9%; 95% CI: 24.5-60.9%). Primary tumor size was significantly higher in patients with metastases (P = 0.017). Bone metastasis by imaging had high correlation with BMAB positivity (P = 0.0002). In addition, the number of bony metastatic sites was significantly higher in patients with a positive BMAB as compared to those with a negative BMAB (median 3.5 and 0.0, respectively; P < 0.001). BMAB may not be required for initial staging of pediatric and young adult EWS patients deemed non-metastatic by imaging. In patients with metastatic disease, there is a high correlation of BM involvement with multiple bone metastases.