Assessment of the effect of different parameters of radiotherapy on treatment outcomes of infiltrative low-grade glioma (Grade II)

The purpose of the study was to develop more effective fractionation regimens and radiation therapy programs in the treatment of infiltrative low-grade gliomas (WHO grade II). Material and methods. The study included 53 patients with morphologically verified supratentorial infiltrative low-grade gliomas (WHO grade II). Diffuse astrocytoma was diagnosed in 35 (66 %) patients, oligoastrocytoma in 7 (13 %) patients and oligodendroglioma in 11 (21 %) patients. Results. The overall survival (OS) was influenced by fractionated radiotherapy regimens (conventionally fractionated versus hypofractionated radiotherapy) (p=0.000) and type of radiotherapy (3D conformal versus 2D radiotherapy) (p=0.023). Multivariate analysis showed a statistically significant difference between the equivalent total dose (LQ-model) and OS (p=0.068). Risk factors proposed by the Association of Russian oncologists (р=0.947) and the extent of surgical excision (р=0.423) had no significant impact on the overall survival. Conclusion. Conventionally fractionated radiation therapy (2 Gy per fraction daily) significantly improved the OS compared to hypofractionated radiotherapy (3 Gy per fraction daily). The value of α/β ratio=6.8 Gy can be used to calculate the total dose using a linear-quadratic model.