Abstract 4015: Primary sites affecting the prognosis of Ewing's sarcoma

Abstract

Abstract Introduction Ewing’s sarcoma (ES) is a small round blue cell malignancy arising from the bone or soft tissue, and most commonly impacts adolescents and young adults. It is difficult to identify those who will likely relapse, however, ES has a very high recurrence rate. Given these realities, the objective of this study was to determine factors influencing the prognosis of ES patients. Methods Clinical and genomic data of 99 patients with ES, were obtained from the cBioPortal. Tumor mutational burden (TMB) and patient survival information were also obtained from the cBioPortal. Results In the data examined, ES had multiple primary sites of disease, including 16 femur, 10 hipbone, 10 rib, 10 tibia, 6 ischium pubis, 5 scapula, 4 fibula, 3 dorsal vertebra, 3 intra-abdominal, 3 lumbar vertebra, and 3 skull. A comparison of survival relationships between different primary sites of ES indicated that overall survival (OS) was significantly different between femur and dorsal vertebra (p = 0.023) and intra-abdominal and hipbone (p = 0.049). However, no significant difference was determined for TMB between the different primary sites. The median value of TMB was 0.23. Data were divided into two groups: high TMB (TMB-H,≥ 0.23 muts/Mb) and low TMB (TMB-L, < 0.23muts/Mb). Interestingly, the OS of patients with TMB-L was significantly higher than that of patients with TMB-H (p = 0.049; 59.45 versus 42.00 months). The presence of metastases at the time of diagnosis was associated with poor OS ( p = 0.023;) and was a clinical factor associated with outcomes having statistical significance. Conclusions Given the heterogeneity in outcomes for patients with ES, additional prognostic factors are needed to optimize clinical decision making. Prognosis was different depending on primary site of ES. Patients with ES in hipbone displayed a better prognosis compared to that in abdomen. Similarly, patients with ES in dorsal vertebra had a significantly higher OS than that in femur. As such, the primary site should perhaps be considered during ES treatment, although there was no significant difference between TMB and primary site. Our results indicate that high TMB is associated with inferior survival for ES and may provide insights for clinical practice. Citation Format: Jun-Qing Mao, Dan Zhao. Primary sites affecting the prognosis of Ewing's sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4015.