Associations of supramaximal resection with outcome in glioblastoma across age groups: a report of the RANO resect group.

The oncological role of resection in elderly patients with glioblastoma remains controversial. We evaluated the value of resection in patients ≥65 years with (I) newly diagnosed and (II) recurrent glioblastoma by comparing the prognostic relevance of extent of resection to patients <65 years. The international RANO resect group retrospectively collected patients with newly diagnosed and recurrent IDH-wildtype glioblastoma from ten neuro-oncological centers. Associations of residual tumor with molecular and clinical markers and survival were analyzed. 1260 patients with newly diagnosed glioblastoma were identified, including 512 patients ≥65 years. Lower postoperative contrast-enhancing tumor volumes were favorably associated with survival on uni- and multivariate analyses; however, the associations with outcome were more pronounced in younger patients. Only in patients <65 years, supramaximal resection was associated with more favorable survival (40 vs. 20 months, p=0.001). In 310 patients with first recurrence (≥65 years: 92), maximal resection of contrast-enhancing tumor was associated with favorable outcomes, particularly in younger patients. Neither older nor younger patients had favorable outcome associations of supramaximal resection in the recurrent setting. All findings were confirmed in propensity-score-matched analyses to minimize confounding effects of inherent differences in demographic and clinical markers (including second-line treatments) between older and younger patients. While complete contrast-enhancing tumor resection is prognostic for favorable outcomes in older patients, associations of supramaximal resection with improved outcomes were only retained in younger patients with newly diagnosed disease. Those findings support stratified surgical approaches.