(P 96) LEPTOMENINGEAL RECURRENCE OF EWING'S SARCOMA: A CASE SERIES

Objective: Ewing sarcoma is a rare osseous malignant tumor that most commonly affects children and young adults. The tumor typically arises in the bones of the pelvis, limbs, or spine. Definitive treatment for localized disease often involves a combination of systemic therapy, radiation, and surgical resection. Leptomeningeal recurrence after definitive treatment of Ewing's sarcoma is a known but rare complication. Here we describe the clnical course and treatment outcomes of three patients found to have leptomeningeal disease after initial diagnosis of localized Ewing's Sarcoma

Methods: This was a retrospective case series of three patients with leptomeningeal recurrence of Ewing sarcoma. The patient's medical records were reviewed to obtain demographics, clinical history, pathology reports, imaging, treatment, and outcomes.

Results: Review of two females and one male, with a median age of 36 years. All patients had primary osseous involvement of Ewing sarcoma, with one patient having involvement of the zygoma arch, one patient having a sacral tumor, and one patient having a lumbar spine tumor. All three patients had evidence of extradural extension of the primary tumor. Pretreatment PET/CT imaging was performed in all reviewed cases and was negative for metastatic disease. None of the patients had any clinical evidence of focal neurologic deficits prior to initiation of definitive therapy.

Two patients received initial neoadjuvant chemotherapy, followed by definitive surgery or radiation therapy. The third patient received initial subtotal resection of her sacral tumor, followed by adjuvant chemotherapy and radiation therapy. All three patients eventually developed neurologic deficits with evidence of leptomeningeal disease within 6 months of completing definitive therapy for localized disease. All three patients received spinal proton radiation therapy, which resulted in significant improvement in symptoms. Post-radiation systemic therapy included gemcitabine in one patient and temozolomide/irinotecan in one patient.

Conclusion: This case series highlights the rare but devastating complication of leptomeningeal recurrence of Ewing sarcoma. All three patients in this study received salvage spinal proton radiation therapy, which resulted in significant improvement in symptoms. This study suggests that extradural extension of a primary Ewing’s sarcoma spinal proton radiation therapy may be a promising treatment option for patients with leptomeningeal recurrence of Ewing sarcoma. This study was limited by its retrospective design. A prospective study with a larger sample size is needed to better understand the risk factors for leptomeningeal disease and the optimal treatment strategies. This study highlights the need for prospective studies to better understand the risk factors for leptomeningeal disease and to develop more effective treatment strategies. These studies could help to improve the outcomes for patients with this rare but devastating complication of Ewing sarcoma.