Molecular features reflect clinical outcomes after recurrence in medulloblastoma: a single-institution experience

The relationship between molecular features and clinical courses of medulloblastoma at onset has been recently reported; however, data in a recurrent setting are scarce.

We collected medical records, analyzed molecular genetic data of eight patients with medulloblastoma that recurred between 2014 and 2023 in our institution, and retrospectively analyzed the clinical course. Molecular classification and copy number data were obtained using the Illumina Methylation EPIC array®.

The pathological findings were classic and large cell/anaplastic in six and two cases, respectively. The molecular classifications were sonic hedgehog, Group 3, and Group 4 in two, two, and four cases, respectively. Among Group 3/4 cases, two were subclassified as subclass II and III, which were regarded as poor prognostic. A copy number abnormality of MYC/MYCN amplification was observed in three cases. The cases with poor prognostic molecular features showed worse prognosis than that of others (the median durations from the first diagnosis to recurrence 8.5 months vs. 60 months; p = 0.02857, and the median survival time from recurrent diagnosis 3.5 months vs. 42 months; p = 0.00673). Regarding treatment response, no cases with poor prognostic molecular features showed tumor shrinkage with chemotherapy and/or radiation therapy at relapse, except for one case. In contrast, three cases with non-poor prognostic molecular features have been able to control the disease status for more than 2 years.

The clinical course of recurrent medulloblastoma depends on molecular features. Salvage treatment effectiveness should be evaluated on the basis of molecular genetic background information.