Easy-to-use clinical tool for survival estimation in Ewing sarcoma at diagnosis and after surgery

Accurate survival estimations in Ewing sarcoma are necessary to develop risk- and response adaptive treatment strategies allowing for early decision-making. We aim to develop an easy-to-use survival estimation tool from diagnosis and surgery. A retrospective study of 1314 Ewing sarcoma patients was performed. Associations between prognostic variables at diagnosis/surgery and overall survival (OS), were investigated using Kaplan-Meier and multivariate Cox models. Predictive accuracy was evaluated by cross-validation and Harrell C-statistics. Median follow-up was 7.9 years (95%CI 7.6-8.3). Independent prognostic factors at diagnosis were age, volume, primary tumor localization and disease extent. 5 risk categories (A-E) were identified with 5-year OS of 88% (86-94), 69% (64-74), 57% (50-64), 51% (42-60) and 28% (22-34) respectively. Harrell C-statistic was 0.70. Independent prognostic factors from surgery were age, volume, disease extent and histological response. In categories A-B, 5y OS increased to 92% (87-97) and 79% (71-87) respectively for 100% necrosis and decreased to 76% (67-85) and 62% (55-69) respectively for <100% necrosis. In categories C-E, 5y OS increased to 65% (55-75), 65% (52-78) and 52% (38-66) respectively for ≥90% necrosis and decreased to 38% (22-54), 11% (0-26) and 7% (0-19) respectively for <90% necrosis. We present an easy-to-use survival estimation tool from diagnosis in Ewing sarcoma based on age, volume, primary tumor localization and disease extent. Histological response is a strong additional prognostic factor for OS.