P12.60.a Patient Age Is Related to Favorable Association of Supramaximal Resection With Outcome in Glioblastoma - A Report of the Rano Resect Group

BACKGROUND 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. MATERIAL AND METHODS 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 on survival were analyzed. RESULTS 1260 patients with newly diagnosed glioblastoma were collected, including 512 elderly patients defined by an age of ≥65 years. While MGMT promotor methylation and subcortical tumor localization were both prognostic for favorable outcome and similar between age cohorts, KPS and second-line treatments differed between elderly and younger patients. Lower postoperative contrast-enhancing tumor volumes were favorably associated with survival on uni- and multivariate analyses; however, the effects on outcome were more pronounced in younger patients. Only in patients <65 years, supramaximal resection translated into more favorable survival (40 [CI: 22-56] vs. 20 [CI: 18-21] months, p=0.001). In 310 patients with first recurrence of a previously resected glioblastoma (including 92 patients ≥65 years), maximal resection of contrast-enhancing tumor was associated with favorable outcome particularly in younger patients (p=0.001) while neither elderly nor younger patients had definitive evidence for favorable effects of supramaximal resection. 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 elderly and younger patients. CONCLUSION While complete contrast-enhancing tumor resection is prognostic for favorable outcome in patients ≥65 years, the associations of extensive (supramaximal) resection with improved outcomes are less pronounced compared to younger patients. Those findings highlight the relevance of tailored resection strategies in elderly patients, supporting individualized goals for extent of resection by acknowledging age.