[Extent of resection in patients with glioblastoma].

Objective: To investigate the impact of resection quality on subsequent survival of patients with glioblastoma.

Material and methods: There were 141 patients with morphologically confirmed glioblastoma (grade 4). Fractionation with the prescribed dose of 2 and 3 Gy was alternately used (pairwise modeling strategy). Total resection was performed in 29.8% of patients (EOR: 100%; n=42), subtotal - 56.7% (EOR: 70-99%; n=80). Extent of resection 1-69% was registered in 19 patients (13.5%).

Results: As of December 2022, 124 out of 141 patients (87.9%) were diagnosed with primary progression, 101 (71.6%) ones died. We analyzed the threshold role of EOR. The most informative level was 70% (p=0.002). EOR 100% was followed by median overall survival about 32.2 months (95% Cl: 15.3-49.1), EOR 70-99% - 21.3 months (95% Cl: 15.1-27.5), EOR 1-69% - 10.3 months (95% Cl: 3.8-16.9; p=0.003). Fractionation mode with the prescribed dose of 3 Gy partially eliminated significance of EOR (p=0.148) in contrast to standard fractionation (p=0.015). Tumor growth in the interval between surgery and radiotherapy (REP) reduces significance of EOR (p=0.042). Inclusion of second-line therapy with bevacizumab in multivariate analysis model (OR=0.488; p=0.002) makes EOR less significant (OR=0.749; p=0.085) in contrast to REP (OR=2.482; p<0.0001).

Conclusion: To date, the principle of maximum safe resection remains fundamental in neurosurgery. EOR about 70% is sufficient regarding overall survival, but total resection should be sought if possible.