Surgical resection of medulloblastoma: How much is sufficient and necessary? A systematic review of literature

Background The risk stratification after surgery for patients with medulloblastoma has been based on three variables, ie, age, metastasis, and residual tumor following surgery for a long time. Out of these, there is lack of consensus regarding the impact of extent of resection (EOR) on survival. Aim In this study, we aim to systematically review the impact of EOR on the prognosis and long‐term outcomes of medulloblastoma. Methods and results The authors performed a systematic review of prospective studies published in PubMed that evaluated the role of EOR on long‐term outcomes in terms of overall survival (OS) and progression‐free survival (PFS). The data of the identified studies were systematically analyzed. Ten prospective studies fulfilling the eligibility criteria were identified. Five studies found no significant difference in either OS or PFS with EOR. On the other hand three studies found a clear association with higher OS and PFS with gross total resection (GTR). One study found PFS to be correlated with <1.5 cm 2 residual but not with >90% resection. Another study noted that EOR is important for PFS but not for OS. There was significant heterogeneity in the assessment criteria and classification of EOR across the studies. Conclusions There is a need to update and standardize the criteria to classify EOR according to current understanding of the disease, including its molecular subtypes. Prospective studies evaluating the impact of EOR in relation with molecular subtyping will help in deciding the future management algorithms for medulloblastoma.