(P 292) CRANIOVERTEBRAL EWINGS SARCOMA WITH MENINGEAL INFILTRATION - A CLINICAL OUTCOME ANALYSIS

Objective: Cranial and vertebral bones are uncommon site for primary Ewing’s sarcoma (ES) to occur as a primary. We report the outcomes and patterns of failure of cranio-vertebral ES (CVES) with meningeal infiltration (intracranial or intraspinal component).

Methods: We conducted a retrospective audit of patients of CVES treated across two institutes of Tata Memorial Centre, Mumbai from 2011 to 2024, approved by the Institutional Ethics Committee. The diagnosis of CVES – cranial or vertebral origin and histological confirmation, was ratified in a multi-disciplinary tumor board. All patients were radiologically evaluated with localized MR spine and PET-CT for staging. Patients treated with curative intent Ewing’s sarcoma chemotherapy regimen (VAC/IE based), focal radiotherapy (RT) and/or decompressive surgery were included in this study.

Results: Thirty-eight patients were eligible for the study with a median age 12 years (IQR: 7-14), 20 patients (52.6%) being males. Majority had a vertebral primary (89.5%, n=34 patients). Neurological deficits (motor weakness, sensory loss, bowel/bladder retention or incontinence) were seen in 20 patients at presentation. All patients underwent local MRI and whole-body PET-CT. Five patients had systemic metastases at presentation (lungs – 4, lymph nodes – 1) at presentation. Definitive RT was delivered to the primary in all patients with a dose of 45-55.8Gy in conventional fractionation. Of the 20 patients who had neurological deficits at presentation, 14 patients had almost complete recovery, while the remaining four patients had only partial recovery. The most common pattern in the 18 patients who had a relapse was local recurrence (7) followed by systemic metastases (6), CNS dissemination (2) and combined (3: local recurrence + systemic/ local recurrence + CNS dissemination). At the time of analysis, 22 patients were alive (including two with disease). The 5-year local control (LC), progression free survival (PFS) and overall survival (OS) were 69.1 + 9.5%, 50.2 + 9.4% and 65 + 9.2%, respectively.

Conclusion: CVES is a rare and high-risk presentation of Ewing’s sarcoma with outcomes inferior to other primary sites. While local and systemic failures remain predominant, CNS dissemination—though less frequent—is a noteworthy pattern of relapse.