Abstract
BACKGROUND: Local treatment of pelvic Ewing Sarcoma (EWS) is czhallenging due to complex anatomy and potential complications. Local therapy may be deferred to maintain chemotherapy dose-intensity, but the impact of this delay on outcomes remains unclear. METHODS: A systematic review using the PICO model evaluated whether delayed local therapy affects long-term outcomes in localized pelvic EWS. Ovid Medline, Ovid Embase, and Cochrane Central databases were searched through June 2024. Studies were screened by two independent reviewers for quantitative and qualitative data extraction. RESULTS: Of 1849 studies screened, eight eligible studies including 2618 patients were identified; none were pelvic-specific. When specified, 1-18% had pelvic primaries. All studies were retrospective with substantial heterogeneity in endpoints. Seven of eight studies indicated delayed local therapy was associated with reduced event-free survival (EFS) and/or overall survival (OS). In the largest study (Lin et al.) of 1319 EWS patients, delayed local therapy > 16 weeks was associated with significantly reduced OS (HR 1.41, CI 1.11-1.80, p = 0.005). CONCLUSION: This systematic review highlights the importance of multidisciplinary coordinated care during initial chemotherapy to optimize local therapy timing, which may impact outcomes. Further studies are needed to assess timing significance, particularly for pelvic EWS.