High-grade gliomas (HGGs) are devastating tumors associated with one of the worst prognoses in oncology. Glioblastoma multiforme (GBM) is the most frequently reported histologic type, with a median survival after surgery and combined treatment with chemotherapy and radiotherapy of 12–16 months. Several studies have shown that the extent of resection (EOR) of the contrast-enhancing part of the tumor improves survival in patients with HGGs, although the quest to achieve optimal oncologic outcomes must be tempered with the neurologic result following radical resection. To date, limited evidence exists on the relationship between EOR and level of clinical benefit for patients with HGGs. Brown et al. reported the results of a systematic review of the literature aimed at determining whether greater EOR is associated with improved 1-year and 2-year overall survival and 6-month and 1-year progression-free survival in patients with GBM. The analysis revealed 37 studies suitable for inclusion. The authors found that gross total resection (GTR) for GBM reduces 1-year and 2-year mortality, thus supporting the use of GTR over subtotal resection and biopsy. However, it should be considered that these findings were based primarily on data from retrospective studies, which are associated with a high risk of bias. Furthermore, in the studies included in the analysis reported, EOR was almost defined arbitrary with ambiguous or unproven methodologies.12 Also, most of the studies considered have been carried out without the current technologic armamentarium.
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