Introduction: In a randomized controlled trial (RCT) the use of an intraoperative MRI (iMRI) led to improved rates of complete tumor removal. In this study, gross total removal (GTR) was associated with longer progression-free survival. However, overall survival (OS) was not addressed in the primary analysis.
Methods: We performed a secondary analysis of survival data of patients with histologically proven and previously untreated glioblastomas (GBM) who participated in a RCT comparing conventional with iMRI guided microsurgery that was published before. Tumor volumes were calculated from preoperative and early postoperative MRI scans and assessed for extent of resection by an independent and blinded radiologist. Adjuvant therapy was administered according to interdisciplinary board decision and patient preference.
Results: We analyzed imaging and survival data of 37 patients with a median age of 56 years (range: 30-76). No patient was lost to follow-up. Median OS was 18.9 months. While the use of iMRI itself did not affect outcome (p=0.44), patients undergoing iMRI-guided resection had a higher rate of GTR (p<0.05) as well as complete resection of contrast enhancing tumor (CRET; p<0.01). CRET was associated with improved overall survival (24.9 vs. 13.4 months, p<0.05). There was a trend for clinical status influencing OS: patients with KPS =90 had an OS of 24.1 months, while it was only 13.4 for patients with KPS=80 (p=0.06). MGMT promotor methylation status did not affect OS on a statistically significant level (p=0.33). Likewise, patient age was not a statistically significant factor concerning OS (p=0.48). Following Cox regression analysis, CRET in contrast to KPS remained the only statistically significant factor influencing OS (p<0.05).
Conclusions: Our data corroborate recent findings that CRET is an independent prognostic factor in GBM. Use of iMRI helps to achieve a greater extent of resection and thus directly impacts patient outcome.
Patient Care: Our data show the importance of radiologically complete but not subtotal removal of primary glioblastomas. Intraoperative MRI is associated with improved extent of resection and thus impacts survival.
Learning Objectives: importance of complete resection of contrast enhancing tissue (CRET)
influence of intraoperative MRI on the extent of resection