Innovative Hypofractionated Stereotactic Regimen Achieves Excellent Local Control with No Radiation Necrosis: Promising Results in the Management of Patients with Small Recurrent Inoperable GBM

Pattern of recurrence after fractionated stereotactic reirradiation in adult glioblastoma

BACKGROUND

Glioblastomas all eventually relapse after initial treatment, and an option to treat these recurrences is fractionated stereotactic reirradiation (fSRT). The location of recurrences following reirradiation has not been studied for fSRT delivered by a dedicated stereotactic device. We aimed to analyze these locations to better elucidate safety margins, dose and fractionation regimens.

METHODS

We retrospectively analyzed the data of patients with glioblastoma recurrence that had been reirradiated by fSRT in October 2010-December 2020, in 25 Gy in 5 fractions delivered by a CyberKnife® at Institut de Cancérologie de Lorraine. We matched the images of the post-fSRT relapse with the stereotactic radiation treatment planning scan to determine the relapse location.

RESULTS

The location of recurrences after fSRT was "out-field" in 43.5%, "marginal" in 40.3%, and "in-field" in 16.1% of patients (N = 62). A GTV-PTV margin of 1 mm (versus 2-3 mm, HR = 0.38 [0.15-0.95], p = 0.037) and a PTV volume of ≥ 36 cc (HR = 5.18 [1.06-25.3], p = 0.042) were significantly associated with the "marginal" recurrences. Being ≥ 60 years old at initial treatment (HR = 3.06 [1.17-8.01], p = 0.023) and having one or more previous recurrences (HR = 5.29 [1.70-16.5], p = 0.004) were significantly associated with "out-field" recurrences. The median PFS from fSRT was 3.4 months, and OS from diagnosis and from fSRT were 25.7 and 10.8 months respectively.

CONCLUSION

Reirradiation of glioblastoma recurrence by fSRT with 25 Gy in 5 fractions provides good local control.

Neuroimaging classification of progression patterns in glioblastoma: a systematic review

BACKGROUND

Our primary objective was to report the current neuroimaging classification systems of spatial patterns of progression in glioblastoma. In addition, we aimed to report the terminology used to describe 'progression' and to assess the compliance with the Response Assessment in Neuro-Oncology (RANO) Criteria.

METHODS

We conducted a systematic review to identify all neuroimaging studies of glioblastoma that have employed a categorical classification system of spatial progression patterns. Our review was registered with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) registry.

RESULTS

From the included 157 results, we identified 129 studies that used labels of spatial progression patterns that were not based on radiation volumes (Group 1) and 50 studies that used labels that were based on radiation volumes (Group 2). In Group 1, we found 113 individual labels and the most frequent were: local/localised (58%), distant/distal (51%), diffuse (20%), multifocal (15%) and subependymal/subventricular zone (15%). We identified 13 different labels used to refer to 'progression', of which the most frequent were 'recurrence' (99%) and 'progression' (92%). We identified that 37% (n = 33/90) of the studies published following the release of the RANO classification were adherent compliant with the RANO criteria.

CONCLUSIONS

Our review reports significant heterogeneity in the published systems used to classify glioblastoma spatial progression patterns. Standardization of terminology and classification systems used in studying progression would increase the efficiency of our research in our attempts to more successfully treat glioblastoma.