MDB-11. DOES THE INTRAOPERATIVE ASSESSMENT OF SITE OF ORIGIN OF MEDULLOBLASTOMA ALLOW FOR A TAILORING OF THE NEUROSURGICAL STRATEGY? DATA FROM A RETROSPECTIVE SINGLE-CENTER ASSESSMENT AND PROPOSAL OF A PROSPECTIVE MULTICENTER STUDY

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Abstract BACKGROUND Developmental gene expression data from medulloblastoma (MB) suggest that WNT-MB originate from the region of the embryonic lower rhombic lip (LRL), whereas SHH-MB and non-WNT/non-SHH MB arise from cerebellar precursor matrix regions. This study aims to analyze detailed intraoperative data with regard to the site of origin (STO) and compare these findings with the hypothesized regions of origin associated with the molecular group. METHODS A review of the institutional database identified 58 out of 72 pediatric patients who were operated on a MB at our department between 1996 and 2020 that had a detailed operative report, surgical video as well as clinical and genetic classification data available for analysis. The STO was assessed based on intraoperative findings. RESULTS Using the intraoperatively defined STO, “correct” prediction of molecular groups was feasible in 20% of WNT-MB, 60% of SHH-MB and 71% of non-WNT/non-SHH MB. The positive predictive values of the neurosurgical inspection to detect the molecular group were 0.21 (95% CI 0.08–0.48) for WNT-MB, 0.86 (95% CI 0.49–0.97) for SHH-MB and 0.73 (95% CI 0.57–0.85) for non-WNT/non-SHH MB. CONCLUSION In our series of 58 well-documented cases, the intraoperative assessment of the STO could not reliably predict the molecular group. Thus, the current evidence does still not allow for intraoperative group-specific risk stratification that would enable tailoring the neurosurgical strategy to the prognostic and predictive profile of the patient. Prospective multicenter assessments are necessary to systematically evaluate the growth pattern and site of origin of medulloblastoma. Accordingly, a study protocol of an international cohort study will be presented.