Double-labelling immunohistochemistry for MGMT and a “cocktail” of non-tumourous elements is a reliable, quick and easy technique for inferring methylation status in glioblastomas and other primary brain tumours

Table 1 Previous studies

Author and year	Tumour type	Cut off value for IHC	Low MGMT protein expression predictive of:		MGMT IHC compared to molecular gold standard	Molecular test	Correlation between IHC and molecular test
Author and year	Tumour type	Cut off value for IHC	Progression free survival (PFS)	Overall survival (OS)	MGMT IHC compared to molecular gold standard	Molecular test	Correlation between IHC and molecular test
Nakasu et al. 2004 [7]	69 high-grade gliomas (grades III and IV)	10%	-	Yes	No	-	-
Brell et al. 2005 [11]	93 anaplastic gliomas: 75 AAs and 18 with oligodendroglial component	5%	No	Yes	Yes	MS-PCR	No
Chinot et al. 2007 [21]	28 GBMs	35%	Yes	Yes	No	-	-
Capper et al. 2008 [22]	75 primary GBMs	15%	Yes – median survival		No	-	-
Preusser et al. 2008 [6]	164 GBMs	10%	-	No	Yes	MS-PCR	Poor agreement
Rodriguez et al. 2008 [23]	50 GBMs	10%	No	No	Yes	MS-PCR	No
Karayan-Tapon et al. 2010 [24]	81 GBMs	15%	No	No	Yes	MS-PCR	-
						SQ-PCR	No
						Pyrosequencing	Yes
						Q-RT-PCR	Yes
Quillien et al. 2012 [5]	100 GBMs	23%	Yes	Yes	No	-	-

The table shows previous studies where MGMT IHC has been performed. The cut-off value was the percentage of MGMT-positive tumour cell nuclei (assessed by eye). The correlation of IHC with progression-free survival (PFS) and overall survival (OS) and comparison with a molecular gold standard (where applied) are also shown.
Abbreviations: AA anaplastic astrocytoma, GBM glioblastoma multiforme, MS-PCR methylation-specific polymerase chain reaction, Q-RT-PCR quantitative real-time polymerase chain reaction, SQ-PCR semi-quantitative polymerase chain reaction.

ISSN: 2051-5960