Radiographic tumor response in pediatric patients with newly diagnosed localized (LOC) or metastatic (MET) Ewing’s sarcoma (EWS) following neoadjuvant chemotherapy

Abstract

20008 Background: Standard treatment for EWS includes vincristine, doxorubicin, cyclophosphamide (VDC) alternating with ifosfamide and etoposide (IE). Using this therapy, overall survival is 70% in patients with LOC EWS and 30% in patients with MET EWS. We compared the radiographic response to VDC and IE in patients with LOC or MET EWS. Methods: We conducted a randomized trial comparing pegfilgrastim to filgrastim in patients treated with VDC (cycles 1, 2, 5, 9, 11, 13) and IE (cycles 3, 4, 6–8, 10, 12, 14). Local control with radiation or surgery was initiated after cycle 5. We assessed radiographic response after VDC (C1,2) and IE (C3,4) using 1-dimensional (RECIST) and 2-dimensional (WHO) criteria. Measurements were performed using MEDx. Results: Twenty-one patients with EWS, median age 20y (6–25y), were enrolled; 16 were evaluable for this analysis. Primary tumors were in extremity (n=5) or central axis (n=11). Eight patients had MET disease (pulmonary only, n=4). Median (range) decrease in tumor size by WHO after C4 was 61% (40–92%) for LOC and 83% (47–94%) for MET. Decrease by treatment is presented in the table . Overall responses after 4 cycles for LOC patients were 5 PR, 3 SD using RECIST, and 6 PR, 2 SD using WHO. For MET patients, overall responses were the same using RECIST and WHO, 7 PR, and 1SD. Conclusion: Patients with MET EWS responded as well as those with LOC EWS after 4 cycles of neoadjuvant chemotherapy. Similar overall response was demonstrated using RECIST or WHO. Tumor response after VDC was greater than after IE, possibly due to sequence of administration, but patients had continued tumor response with IE. [Table: see text] No significant financial relationships to disclose.