Tumour Size, Metastasis and Age as Prognostic Factors in Adult Ewing Sarcoma: A Single-Centre Retrospective Cohort Study

Background Prognostic data on adults with Ewing sarcoma are limited, and the prognostic value of the AJCC 8-cm size threshold has not been tested in this population. We aimed to determine overall survival (OS) and its prognostic factors in adults with Ewing sarcoma. Methods Fifty-five patients aged ≥ 18 years with histologically confirmed Ewing sarcoma treated at a single orthopaedic oncology centre in 2011–2021 were reviewed retrospectively. OS was analysed with the Kaplan–Meier method, the log-rank test and univariable and multivariable Cox regression; tumour size was also assessed with receiver operating characteristic (ROC) analysis. Results Median age was 22 years (range 18–65), and 24 patients (43.6%) had metastases at diagnosis. All received neoadjuvant and adjuvant VDC/IE chemotherapy. During a median follow-up of 7 years, 27 patients died; 5-year OS was 54.5% (95% CI 40.6–66.6). Metastasis (5-year OS 29.2% vs 74.2%) and tumour size ≥ 8 cm (16.0% vs 86.7%) were associated with poorer survival (both p < 0.001). In multivariable analysis, tumour size ≥ 8 cm was an independent prognostic factor (HR 9.04; 95% CI 3.06–26.72). In an exploratory model, age (HR 2.35 per 10 years; 95% CI 1.41–3.90) and metastasis (HR 2.75; 95% CI 1.02–7.40) were also independent factors. Tumour size predicted 5-year mortality with an area under the curve of 0.92; the optimal cut-off was 8 cm. Conclusions In adults with Ewing sarcoma, tumour size ≥ 8 cm, metastasis at diagnosis and older age are associated with poorer OS. The 8-cm threshold is a simple tool for risk stratification; multicentre validation is needed.