gms | German Medical Science

Objective: The extent of resection (EOR) has been established as the most important prognosticator for survival in primary and also recurrent glioblastoma (GBM) treatment. Intraoperative MRI (iMRI) guidance supports the surgeon to safely increase EOR and to obtain gross total resection (GTR) whenever deemed possible. In this study we analyzed how frequently GTR can be achieved with routine iMRI guidance in a prospective cohort of primary and recurrent GBM.

Method: We scanned our prospective iMRI data base for primary or recurrent GBM cases that were scheduled for a complete tumor resection. The operating surgeon verified safe feasibility of GTR and the aspired EOR was volumetrically documented on neuronavigation images. Preoperative, intraoperative and postoperative volumetric data was compared and a case-by-case analysis of EOR was performed.

Results: Overall, 123 GBM cases were identified, 75 were primary GBM, recurrences were treated in 48 cases. Mean initial tumor volume was 32,57±28,37cm³ with larger volumes in primary than in relapse surgery (36,92±28,41cm³ vs. 25,82±27,23cm³, respectively). Among all 123 cases, mean final EOR was 99,7%±1,18%. Residual tumor was frequently revealed on iMRI and additional resection was performed in 65,9% of cases. Neither mean EOR, nor rate of additional resections were significantly different in primary compared to recurrent surgery. An overall case-by-case analysis revealed that GTR (=100%EOR) could be reached in 82,1% of cases (101/123). GTR could be achieved in 81,3% of primary GBM (61/75) and 83,3% of recurrent GBM (40/48). In 22/123 (17,9%) cases, resection was incomplete with 17 patients receiving an EOR between 98% and 100%. EOR was less than 98% in only 5/123 cases (4,1%) in this series (i.e. 2 primary GBM, 3 recurrent GBM). No patient received an EOR of less than 97%.

Conclusions: In this series, 123 consecutive GBM patients with an intended complete tumor resection were operated under routine iMRI guidance. IMRI guided resections stand out with a constant high mean EOR of 99,7%±1,8% regardless whether primary or recurrent disease was treated. Surgical accuracy is improved, planned GTR is achieved in 82,1% of cases and only 4,1% of patients receive resections of less than 98% EOR. Considering that survival advantage increases along with EOR and seems to be especially accentuated between 98% and 100% EOR, these results are promising and thorough analysis of survival data is currently under investigation.