Extent of resection and its association with overall survival in newly diagnosed IDH wildtype glioblastoma treated with concomitant radiochemotherapy: a systematic review and meta-analysis.

Background: Extent of resection (EOR) is a well-known prognostic factor in patients with newly diagnosed IDH-wildtype glioblastoma. However, reported survival times across resection categories vary between reports, and outcomes of submaximal or supramaximal resection remain less well defined. Methods: We conducted a systematic review and meta-analysis on the association between EOR and overall survival (OS) in patients with newly diagnosed IDH-wildtype glioblastoma treated with chemoradiotherapy. Studies were included if OS was reported by EOR category. Risk ratios (RRs) for 1- and 2-year survival were pooled using a random-effects model. Study quality was assessed using the Newcastle-Ottawa Scale. Results: Thirty-one studies involving 26,167 patients were included. Supramaximal resection (SupraMR) was associated with significantly improved 2-year survival compared to maximal CE resection (MR) (RR 0.70, 95 % CI 0.55-0.88). Compared to submaximal resection (subMR), MR was associated with higher 1-year survival (RR 0.59, 95 % CI 0.53-0.67) and 2-year survival (RR 0.82, 95 % CI 0.77-0.87). Biopsy alone was associated with the poorest outcome. Findings remained robust in sensitivity analyses excluding SEER and RTOG cohorts. Conclusions: Increasing EOR seems to be associated with improved survival in newly diagnosed IDH-wildtype glioblastoma. SupraMR offers the greatest benefit, while submaximal resection appears to be more favorable than biopsy. These findings support the prognostic relevance of EOR and underscore the need for prospective studies with standardized resection classifications. The balanced summary of survival data for each resection class provided in this review can serve as a basis for effect estimation and sample size calculations in future trials.