Can we make it up? - second-look surgery due to post-operative residual tumour in patients diagnosed with diffuse glioma

PURPOSE: Complete resection (CR) of contrast-enhancing (CE) and non-contrast-enhancing (nCE) tumour compartments is a key prognostic factor in diffuse gliomas. However, despite an intraoperative impression of CR, early postoperative MRI may reveal residual tumour. This study evaluated outcomes of patients undergoing early second-look surgery for unplanned residual tumour volume. METHODS: Patients undergoing surgery for diffuse gliomas between 2013 and 2023 were screened for surgical re-intervention within six weeks after initial resection. Patients undergoing early second-look surgery due to unplanned residual tumour on postoperative MRI were included. Volumetric MRI analyses, RANO resection classification, functional neurological outcomes, perioperative complications, and survival were assessed. RESULTS: Among 1.558 glioma patients (CNS WHO grade 2–4), 447 underwent multiple surgeries, of whom 46 received second-look surgery for residual tumour. Resection status shifted from 80.4% submaximal after first surgery to supramaximal or maximal resection in 86.96% after second-look surgery. Residual tumour volumes were significantly reduced for both T1-CE and T2-nCE components (p < .001). Functional and neurological status remained stable (KPS and NIHSS, p > .5). In newly diagnosed glioblastoma patients (n = 28), RANO class 1 after second-look surgery was associated with longer overall survival compared to RANO 2B (13.8 vs. 8.0 months; p = .043). The 2- and 3-year OS rates were 33.34% and 16.67% in RANO class 1, while no patients in RANO class 2B survived beyond 2 years. CONCLUSION: Early second-look surgery for unplanned residual tumour enables a high rate of (supra-)maximal resections without compromising functional outcomes and may improve survival in selected patients.