AYA rhabdomyosarcoma: Evolving changes in regional service delivery impacting on outcomes and meningeal disease

e22006 Background: Rhabdomyosarcoma (RMS) is a rare and aggressive sarcoma with a variable prognosis dependent upon age, histology, PAX-FOXO1 translocation status, site, stage of disease and treatment. RMS has a peak age of incidence in adolescents and young adults (AYA). Centralisation of care in the UK has impacted on treatments given and outcome. With extended outcomes in an age associated with poor prognosis we have seen increased rates of meningeal disease as a late event. We examined factors predisposing to meningeal involvement and associated outcomes in changing treatments. Methods: Retrospective review of AYA with RMS, treated between 2004 and 2022 at a regional AYA center serving a population of 2.5 million. Results: 17 patients (9 males, 8 females) were identified (median age 18). At diagnosis, 5 patients had locally advanced disease and 11 had metastases. Meningeal disease developed in 11/17 after a median of 11 months (range 6-87) from diagnosis. Overall survival was 14 months (range 14-87) for those who developed meningeal disease versus 54 months (range 6-167, not reached in 3) in those who did not. Following meningeal involvement, survival ranged from 0-7+ months. Histology of those with meningeal disease: embryonal (5) alveolar (6). 5/6 patients with alveolar RMS (ARMS) had FOXO1 gene rearrangement. Presentation of meningeal disease included: headaches (7), visual phenomena (3), nausea/vomiting (2), unusual chest or back pain (5). Risk factors included bone marrow infiltration (2/2), para-meningeal/orbital primary (4/4), and widespread metastatic or locally advanced primary disease 10/11. 10/11 received treatment with radiotherapy and/or chemotherapy with symptomatic benefit. Conclusions: Meningeal disease in RMS occurs more frequently in those with a primary close to the brain and with bone marrow involvement. Site and extent of primary disease was more predictive than histology for meningeal disease, but not of survival. Adaptation to longer initial treatments with maintenance therapy has increased survival in AYA RMS. Early recognition of key warning symptoms is important to guide prognostication and symptom control.