Tumour burden drives outcomes in Ewing sarcoma: Real-world clinicopathological profile, radiotherapy utilisation, and survival analysis from North India

Objectives: Ewing sarcoma (ES) is a rare but highly aggressive small round-cell malignancy predominantly affecting children and young adults. Data on real-world treatment outcomes from low- and middle-income countries (LMICs) remain scarce. This study aims to characterise the clinicopathological profile, treatment patterns, and survival outcomes of ES patients treated at a regional tertiary cancer centre in North India, and to identify independent prognostic factors for overall survival (OS) and progression-free survival (PFS). Material and Methods: We retrospectively analysed 57 patients with histologically confirmed Ewing sarcoma treated between July 2020 and June 2024 using a standardised multimodal protocol. All patients received systemic chemotherapy vincristine, doxorubicin (Adriamycin), and cyclophosphamide alternating with ifosfamide and etoposide(VAC-IE), with local treatment comprising surgery, radiotherapy (RT), or combined modality therapy based on multidisciplinary tumour board decisions. Results: The median age was 18 years (range: 11-57); males predominated (M: F = 1.85:1). Axial skeletal sites accounted for 59.6% of tumours, and 28.1% of patients presented with metastatic disease. Notably, 61.4% had a symptom duration exceeding three months prior to diagnosis, reflecting characteristic diagnostic delays in LMIC settings. The 3-year OS and PFS rates were 60.7% and 51.5%, respectively. Tumour volume >200 mL (hazard ratio [HR]: 16.21; 95% confidence interval [CI] 3.55–73.96; p = 0.001) and tumour diameter >8 cm (HR 13.35; 95% CI 3.73–47.8; p = 0.002) were the only independent adverse prognostic factors on multivariate analysis for both OS and PFS. Conclusion: Tumour burden at presentation is the single most powerful driver of inferior outcomes in ES, underscoring the critical need for early diagnosis and prompt referral in LMICs. Radiotherapy played a central and versatile role in local disease management across all risk categories. Our results, obtained with a non-dose-dense chemotherapy regimen, are comparable to other published Indian series and corroborate global prognostic benchmarks. Strengthening cancer awareness, improving diagnostic infrastructure, and establishing standardised multidisciplinary care pathways are essential steps toward narrowing outcome disparities.