For patients with confirmed Ewing tumor of bone (ETB), pretreatment staging studies should include magnetic resonance imaging (MRI) and/or computed tomography (CT) scan of the primary site, depending on the site. Despite the fact that CT and MRI are both equivalent in terms of staging, use of both imaging modalities may help radiation therapy planning.[1] Additional pretreatment staging studies should include bone scan, CT scan of the chest, and bone marrow aspiration and biopsy. Staging modalities under evaluation but not required on current clinical trials include fluorodeoxyglucose positron emission tomography and molecular analysis of bone marrow for the presence of fusion transcript. In certain studies determination of pretreatment tumor volume is an important variable (Euro-Ewings 99).

For ETB, the tumor is defined as localized when, by clinical and imaging techniques, there is no spread beyond the primary site or regional lymph node involvement. Continuous extension into adjacent soft tissue may occur.

References

1. Panicek DM, Gatsonis C, Rosenthal DI, et al.: CT and MR imaging in the local staging of primary malignant musculoskeletal neoplasms: Report of the Radiology Diagnostic Oncology Group. Radiology 202 (1): 237-46, 1997.  [PUBMED Abstract]