GTR versus STR in Glioblastoma: A Meta-Analytic Umbrella Review on Survival Outcomes

Introduction: Glioblastoma (GBM) is the most common malignant brain tumor in adults. Given a lack of level 1 evidence directly addressing the question, no clear consensus exists regarding what extent of resection is necessary to optimize overall survival outcomes in patients. The aim of this umbrella review is to aggregate existing meta-analyses (MAs) to provide an expanded analysis of overall survival in patients undergoing subtotal resection (STR) versus gross total resection (GTR).

Methods: A systematic literature search conducted using specific search criteria across PubMed, Scopus, and Web of Science databases yielded a total of 441 studies, with four MAs suitable for inclusion. Data were analyzed using metaumbrella R package employing equivalent Hedges' g values, with overall survival as the outcome. The quality of each MAs was assessed using AMSTAR2, with scores ranging from 0 to 11. The Ioannidis criteria were utilized to ascertain the credibility of evidence.

Results: The quality assessment demonstrated that all four studies were of high quality, with a mean AMSTAR2 score of 10.25. When pooled, the MAs revealed a statistically significant difference in overall survival favoring GTR over STR. However, upon evaluating the credibility of the evidence with the Ioannidis classification system, the survival advantage of GTR was found to have weak credibility and graded as Class III.

Conclusion : Our umbrella review offers a comprehensive summary of existing evidence on the impact of resection extent on overall survival in GBM patients. GTR has a slightly higher overall survival compared to STR, but the credibility of the evidence is weak. This highlights inconsistencies within the literature, underscoring the need for further research in this area.