Table 3. Levels of evidence for MGMT promoter methylation testing using various DNA-based methods. Definitions and discussion of evidence levels A, B, C and D are given in [24]; in brief, a biomarker needs to reach evidence level B or higher for both analytical and prognostic or predictive performance to have sufficient clinical utility.

Biomarker	Tumor type	Analytical performance	Prognostic clinical performance	Predictive clinical performance
MGMT promoter methylation	Adult glioblastoma	A: PSQ	A: glioblastoma	A: glioblastoma of the elderly
		B:	B:	B:
		C: MSP, MS-MLPA, MS-PCR	C:	C: glioblastoma (all adult patients except elderly)
		D:	D:	D:

MGMT = O6-methylguanine-methyltransferase promoter; MSP = methylation-specific polymerase chain reaction; MS-MLPA = methylation-specific multiplex ligation-dependent probe amplification; PSQ = pyrosequencing.