Extraneuraxial metastases from medulloblastoma: Single-institution outcome analyses

Abstract

Introduction: Novel biological insights have led to consensus classification of medulloblastoma into four distinct molecular subgroups. It is widely accepted that medulloblastomas have a higher propensity for extraneuraxial metastases (ENM) compared to other primary brain tumors. We sought to review our own institutional experience of ENM from medulloblastoma. Materials and Methods: Patients with a histological diagnosis of medulloblastoma and ENM were identified from institutional neuro-oncology database. Patient-, disease-, and treatment-related details were retrieved by retrospective review of medical case records. Results: A total of 573 patients with medulloblastoma were registered from 2005 to 2016, of which 13 patients were detected with ENM. Median age of our study cohort was 17 years (range: 3–25 years) at index diagnosis. Ten (77%) patients had desmoplastic medulloblastoma, while 3 (23%) patients had large-cell/anaplastic histology. Five of 7 (71%) patients with known molecular subgroup affiliation belonged to sonic hedgehog subgroup, while the remaining two (29%) were subgroup 3 medulloblastoma. The median time to development of ENM was 13 months (range: 2–72 months) with common sites being bone (77%), bone marrow (62%), and lymph nodes (46%). Median overall survival after diagnosis of ENM was 2 months (range: 1–25 months) with 1-year survival probability of 23%. Patients with desmoplastic medulloblastoma had longer median overall survival compared to anaplastic histology (4.5 months vs. 1 month; P = 0.07). None of the other putative prognostic factors such as age at ENM, concurrent central nervous system involvement, visceral metastases, or time to relapse impacted overall survival. Conclusions: ENM from medulloblastoma, although rare, is frequently associated with desmoplastic histology. Bone, bone marrow, and lymph nodes are the most common sites of extraneuraxial involvement. Survival outcomes remain universally poor mandating the testing of newer agents and/or novel molecularly targeted therapies.