ID #1042 Prevalence of Therapy-Related Microvascular Lesions in Five-Year Medulloblastoma Survivors

Abstract Background Medulloblastoma treatment typically includes radiation therapy (RT) and chemotherapy (CT), achieving an overall survival rate of ≥ 80%. However, survivors suffer significant longterm morbidities, including progressive cognitive decline. Increasing evidence links therapy-related cognitive decline to delayed microvascular injury resembling accelerated cerebral smallvessel disease. Both CT and RT can cause senescence in cerebromicrovascular endothelial cells, contributing to vascular fragility, blood–brain barrier disruption, neuroinflammation, and white-matter injury. Cerebral microhemorrhages (CMH), detectable on diffusion-weighted imaging (DWI) or apparent diffusion coefficient (ADC) MRI sequences, serve as a marker of such vascular damage. Objective To explore the prevalence of CMH on 5-year followup MRI in medulloblastoma survivors. Secondary aim - compare the prevalence in survivors treated with RT plus CT versus CT alone. Methods Using the electronic medical record, we identified patients diagnosed with medulloblastoma in 2000-2020 who remained relapsefree for at least 5 years after diagnosis. Clinical and treatment data, including RT dose and CT regimen, were reviewed. 5-year follow-up MRIs were evaluated for number of CMH in a double-blinded manner by two independent physicians. Cases with discrepancies of ≥ 2 lesions were adjudicated by a third reviewer. CMH counts were compared between patients treated with RT plus CT and those treated with CT alone. Results Twenty-eight non-relapsed medulloblastoma survivors met inclusion criteria: 4 treated with CT alone and 24 with RT plus CT. The RT+CT group demonstrated an average of 2.5 CMH per patient, compared with 0.5 CMH per patient in the CT-only group. Conclusion Survivors treated with RT plus CT exhibited a greater burden of late-developing microhemorrhages than those treated with CT alone, suggesting more pronounced long-term microvascular injury. These findings indicate neurovascular compromise may contribute to premature vascular aging and cognitive decline and underscore the importance of understanding therapyrelated vascular changes to guide future treatment strategies.