AbstractBACKGROUND AND AIMSReports from low-and middle-income countries (LMICs) indicate lower survival in medulloblastoma (MB), though these studies are mainly from single institutions. This multi-institutional, retrospective study aimed to analyze the outcomes for MB in 9 centers in 8 LMICs.METHODSPatients <18 years old with newly diagnosed MB, treated from January 2014 to December 2018 in Egypt, El Salvador, Malaysia, Mexico, Pakistan, Peru, Philippines, and Uruguay were included. Data on demographics, clinical presentation, treatment and biological characteristics were collected. Factors associated with patient outcomes were analyzed.RESULTSThe study included 330 patients with a median age of 7.7 years. Of these, 49 patients (15%) were <3 years old and 212 (64%) were male. Eighty-eight patients (26%) had experienced symptoms for >3 months at diagnosis. Gross total resection was achieved in 153 (47%) patients. Sixty-three patients (19%) experienced post-operative infections. Eighty-four patients (24%) had metastatic disease at diagnosis. The histologic subtype was not specified in 98 cases (30%), and 25 patients (7%) had molecular subgroups identified. Radiotherapy was administered to 216 patients (64%). The median number of chemotherapy cycles was 8 (range 0-14). There were 64 patients (19%) who abandoned treatment, and 24 patients (7%) died due to treatment-related toxicity. The 5-year event-free survival (EFS) was 44±4%, while the 5-year overall survival was 58±4%. The 5-year EFS for patients <3 years was 42±9%, while 44±4% for older patients (p=0.49). The 5-year EFS for patients with metastasis was 38±7%, while it was 46±4% for patients without metastasis (p=0.13).CONCLUSIONSThis large, multinational cohort of MB in LMICs describes poor outcomes, which may be attributed to delays in care, high abandonment rate, surgical complications, treatment-related mortality and a low fraction of patients receiving radiotherapy. Interventions to build care capacity can be prioritized based on these data.