[Choice of fractionation regimen for Grade IV gliomas depending on rapid early progression].

Objective: To investigate the effect of two fractionation regimens on survival in patients with Grade IV gliomas depending on rapid early progression (REP).

Material And Methods: Fractionation with prescribed doses of 2 and 3 Gy was alternately used in 140 patients with morphologically confirmed Grade IV glioma using a pairwise modeling strategy.

Results: REP was diagnosed in 60 (42.9%) out of 140 patients with Grade IV gliomas and 55 (45.5%) out of 121 patients with glioblastomas. Fatal outcome was observed in 111 (79.3%) patients, 99 (70.7%) ones died from progression of glioma. In case of no REP, the median overall survival as of December 2023 was 32.20 (95% CI 25.7-38.7) months, with REP - only 16.03 (95% CI 13.5-18.6) months (<0.0001). Median survival was slightly lower in patients with glioblastoma - 28.2 and 16.5 months, respectively (<0.0001).

Unlabelled: In patients with Grade IV gliomas and no REP, 3 Gy (=40) fractionation regimen was followed by median overall survival 44.98 (95% Cl 15.3-74.6) months, 2 Gy (=40) - 20.99 (95% CI 9.2-32.7) months (=0.027). In case of glioblastoma, differences between fractionation regimes lose significance - medians 33.7 and 19.7 months, respectively (=0.081). According to multivariate analysis, 3 Gy fractionation regimen is more effective than standard radiotherapy (=0.009) in patients without REP, while significance of isoeffective doses <59.5Gy≥ is slightly lower (=0.020). Radiotherapy on the background of temozolomide is equally important (=0.007).

Unlabelled: In patients with grade 4 gliomas and REP, 3 Gy (=30) fractionation regimen was followed by median overall survival 17.18 (95% CI 14.2-20.2) months, 2 Gy (=30) - 12.88 (95% CI 5.4-20.3) months (=0.849). In case of glioblastoma, Cox model classification matrix looks as follows: fractionation variant (=0.423), isoeffective dose <59.5Gy≥ (<0.0001), temozolomide during radiotherapy (=0.701), functional status (=0.485).

Conclusion: In patients with Grade IV gliomas and no REP, 3 Gy fractionation regimen has significant advantages over standard radiotherapy regarding overall survival. In case of more aggressive course of tumor (REP), higher single dose does not improve treatment outcomes. Isoeffective dose ≥59.5Gy is of great importance.