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Glioblastoma (GB) is the most common primary malignant brain tumor in adults. Despite improvements in survival with aggressive chemoradiation, outcomes remain poor. Though the literature supports the use of standard radiotherapy (SRT) (60 Gy in 30 fractions), several randomized studies have supported the use of hypofractionated regimen especially for elderly patients. The aim of this study was to evaluate the effectiveness and safety of the hypofractionated radiotherapy (HRT) in patients with GB. 

This is a retrospective study analyzing the data of 37 patients with GB treated between 2016 and 2020. The median age was 60 years [15-84] (HRT: 72 years; SRT: 66 years) and the performance score (WHO) was ³ 2 in 64% of cases. The median tumor size was 52 mm [3-9,6]. Adjuvant SRT was performed in 70.3% of cases and HRT (40 Gy in 15 fractions) in 29.7% of cases, depending on age and initial WHO score. Concomitant and adjuvant Temozolamide was administered in 51.4% of cases (only for patients treated by SRT).  The primary end-point was the effectiveness of the HRT evaluation by analyzing the overall survival (OS) and disease-free survival (DFS) rates. Clinical assessment of radiation-induced toxicities was performed at the end of radiotherapy sessions using a questionnaire based on the RTOG clinical scales. Assessement of patients quality of life was based on the EORTC QLQ-BN20 questionnaire.

Median OS was 12 months [5-23] and 6 months [3-13] respectively for SRT and HRT (p = 0.01).  Median DFS was 8 months [1-18] and 2 months [1-6] respectively for SRT and HRT (p = 0.01). Multivariate analysis showed that OS predictive factors were the age (age >60 ans; p=0.003), the WHO score (WHO >=2; p=0.001), the type of adjuvant treatment (RT alone; p<10^-3) and the fractionation regimen (HRT; p=0.001). For DFS, the predictive factors were: the WHO score (WHO >=2; p=0.004), the type of adjuvant treatment (RT alone; p=0.007) and the fractionation regimen (HRT; p=0.006). For older patients (>65 years old), those with larger tumor (>65 mm) or higher WHO score (>=2) there were no survival rates differences between HRT and SRT neither for OS (p=0.2,p=0.09 and p=0.1 respectively) nor for DFS (p=0.6,p=0.1 and p=0.4 respectively). For elderly patients, quality of life and acute radiation-induced toxicities (nausea,vomiting, alopecia and cerebral edema), were similar between SRT and HRT. 

The results of this study show the non-inferiority of HRT compared to SRT in terms of survival and disease control outcomes with less radiation-induced toxicities, especially for older patients and those with poor prognosis factors, maintaining a good quality of life. It could be a reasonable therapeutic approach in elderly patients with less favourably prognosis factors.