Consequences of different approaches to local treatment of Ewing’s sarcoma within an international randomised controlled trial: Analysis of EICESS-92

Abstract

9533 Background: Two national clinical trial groups (NCTG 1 and 2) together undertook a randomised trial (EICESS-92) which addressed chemotherapy treatment options for Ewing’s sarcoma (ES). No significant differences were found in analysis of the randomised trial questions. A significantly greater use of surgery, with or without radiotherapy, to achieve local tumour control was noted in NCTG 1. The influence on overall outcome was investigated. Methods: Univariate and multivariate analysis of the trial data set was undertaken. Patient characteristics, recognised prognostic factors for ES and treatment factors were all examined. Results: In total, 647 patients (pts) were randomised (NCTG 1: 437 pts; NCTG 2: 210 pts). There were no differences between groups in patient characteristics, disease factors or in chemotherapy received. Surgery of the primary tumour (74.6% v 51%) and pre-operative radiotherapy (44.6% v 2.9%) were more commonly used by NCTG1. Radiotherapy alone was more commonly used by NCTG 2 (39% v 19.5%). Five year overall survival (OS) for the whole cohort was 62.1% (95%CI: 58.3 to 66.0). Five year OS was 66.5% (95% CI 62.0–71.1) for NCTG 1 and 54.3% (95% CI 47.3–61.4) for NCTG 2 (p=0.009). OS was best for those selected for surgery alone and worst for those treated with radiotherapy alone (p <0.001). OS was equivalent between groups for each modality of local treatment. Local recurrence rates for NCTG1 were 7.1% vs. 21.4% for NCGT2. Conclusions: Unexpected differences in OS can occur between patient cohorts recruited by study groups co-operating in international randomised trials. Higher rates of local recurrence and poorer survival were seen in NCTG 2. Failure to select or deliver appropriate local treatment modalities for ES may compromise chances of cure. No significant financial relationships to disclose.