Spatial patterns of progression in reported glioblastoma cohorts after upfront chemoradiation and salvage therapy: a systematic review and meta-analysis.

Authors

Rafal Chojak, Noah B Drewes, Katarzyna Slychan, Rimas V Lukas

Published in

Journal of neuro-oncology. Volume 179. Issue 1. Jul 30, 2026. Epub Jul 30, 2026.

Abstract

Spatial patterns of glioblastoma (GBM) progression inform focal salvage eligibility, but interpretation across studies is limited by heterogeneous spatial definitions, high between-study heterogeneity, and incomplete reporting of non-enhancing/FLAIR-dominant progression. We synthesized reported progression-location involvement after upfront radiotherapy/temozolomide (RT/TMZ) and salvage therapy.
We systematically searched PubMed and Scopus from January 1, 2000, to February 1, 2026, and performed arm-level random-effects meta-analysis of logit-transformed proportions. Enhancing progression was harmonized as non-mutually exclusive local/in-field, marginal/field-edge, and distant/out-of-field involvement among evaluable cases, using each study's spatial framework. The supplementary broad escape-pattern construct was defined as reported progression beyond purely local/in-field enhancing failure.
We included 107 studies (122 arms; 10,529 patients). At first progression after upfront RT/TMZ ± TTF, reported local/in-field enhancing involvement among evaluable cases was 79.2% (95% CI 75.7-82.3; k = 94; n = 6,989; I²=84.8%), and distant/out-of-field involvement was 16.9% (95% CI 14.3-19.9; k = 89; n = 6,493; I²=85.2%). After salvage therapy, local/in-field involvement remained the majority pattern reported among evaluable cases (59.8%, 95% CI 52.8-66.4; k = 27; n = 1,572; I²=80.5%), with distant/out-of-field involvement of 17.5% (95% CI 12.9-23.3; k = 21; n = 1,307; I²=75.5%) and a supplementary broad escape-pattern estimate of 38.6% (95% CI 31.9-45.9; k = 27; n = 1,572; I²=80.1%). Non-enhancing/FLAIR-dominant progression was sparsely and likely selectively reported; only six recurrent/salvage arms contributed data, yielding an exploratory pooled estimate of 27.8% (95% CI 12.8-50.3; n = 216; I²=75.7%).
Published GBM cohorts show predominantly local/in-field enhancing progression after upfront therapy (~ 80%) and persistent majority local/in-field involvement after salvage therapy (~ 60%). Standardized reporting of enhancing, non-enhancing/FLAIR-dominant, disseminated, posterior fossa, and brainstem progression is needed.

PMID:
42530690
Bibliographic data and abstract were imported from PubMed on 30 Jul 2026.

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