Chai 2018 (8‐site cohort).

Study characteristics
Study design	Cohort
Study setting	Setting: Chinese Glioma Genome Atlas (CGGA) database Country: China Dates: NR
Selection of participants	Inclusion criteria: diagnosed with WHO grade III or IV glioma; containing MGMT promoter methylation PSQ testing data in detail; including exact MGMT mRNA sequencing data; having received radiotherapy + TMZ treatment; containing overall survival information
Participant characteristics	Sample size: 24 (deaths: NR) Age: median 55; range 29–79 years Sex: 58.3% men KPS: median NR; KPS < 80: 11/24 (45.8%); KPS ≥ 80: 9/24 (37.5%); KPS not available: 4/24 (16.7%)
Tumour characteristics	GBM: 100% First diagnosis: NR Biopsy: 0%; subtotal resection: 50%; total resection: 50% IDH mutant 5/24 (20.8%), IDH wild‐type 18/24 (75.0%), not available 1/24 (4.2%). IDH status combined results of IDH1 and IDH2 testing.
Treatment regimen	Radiotherapy + TMZ
MGMT promoter methylation tests implemented	PSQ
Dates and follow‐up	Timing of MGMT assessment: not explicitly reported, but presumably on freshly frozen tumour samples obtained during resection/biopsy. Start time for follow‐up: NR; follow‐up: median NR; range NR
Notes