Prognostic features of Ewing's sarcoma on radionuclide bone scan after initial treatment

To study short-term changes in the radiopharmaceutical bone scan (BS) appearance of Ewing's sarcoma for indicators of decreased survival or future disease progression.

One-hundred and four patients with non-metastatic Ewing's sarcoma were evaluated at three time points: time of diagnosis (pre-biopsy), after induction chemotherapy (13 weeks) and after radiation therapy (20 weeks). Radiographs, computed tomograms (CTs) and BSs were obtained at each interval. Primary lesion activity and size on BS were evaluated and compared to radiographic and CT findings.

No significant relationship was found at any time point between absolute radiopharmaceutical activity within the primary lesion and either disease progression or patient survival. Relative changes in BS activity between time points were also not significantly related to disease progression or survival despite a significant decrease in activity among the three time points. The size of the BS abnormality compared to the CT abnormality at the primary lesion site was related to both survival and disease progression at the post-induction chemotherapy time point (P = 0.025 and P = 0.014, respectively) with larger BS abnormalities indicating worse prognosis and survival. This relationship lost its significance at the post-radiation time point. No other significant relationship between the relative size of the BS abnormality and the size of the plain radiographic or CT abnormality was detected.

Our data suggest that BS imaging of the primary lesion of Ewing's sarcoma provides little information in terms of predicting long-term survival or disease progression in patients with non-metastatic Ewing's sarcoma.