Table 2 Frequency of MGMT methylation and loss of expression in colorectal cancer
MGMT methylationMGMT expression
Total examined, nMethylated (%)p ValueTotal examined, nLoss (%)p Value
MGMT expression
    Loss210156 (74%)<0.0001
    Intact35743 (12%)Referent
MLH1 methylation
    (+)11556 (49%)0.02
    (−)805298 (37%)Referent
MSI status
    MSI-high13157 (44%)9437 (39%)
    MSI-low7333 (45%)4723 (49%)
    MSS685255 (37%)444158 (36%)
TGFBR2 (only MSI-H tumours)
    Mutated9341 (44%)7031 (44%)
    Wild-type3816 (42%)216 (29%)
CIMP status
    CIMP-high13668 (50%)<0.000110142 (42%)0.04
    CIMP-low353154 (44%)0.000219993 (44%)0.003
    CIMP-0431132 (31%)Referent267161 (30%)Referent
KRAS
    Any mutation321135 (42%)20692 (45%)0.003
    G>A mutation19584 (43%)13262 (47%)0.003
    Non-G>A mutation12651 (40%)7430 (41%)
    Wild-type553205 (37%)368119 (32%)Referent
BRAF
    Mutated11646 (39%)8223 (28%)
    Wild-type758294 (38%)492188 (38%)
KRAS/BRAF
    K(+)B(+)63 (50%)32 (67%)
    K(+)B(−)315132 (42%)20390 (44%)0.02
    K(−)B(+)11043 (39%)7921 (27%)
    K(−)B(−)443162 (37%)28998 (34%)Referent
18q LOH
    (+)23771 (30%)0.000816945 (27%)0.004
    (−)21798 (45%)Referent14561 (42%)Referent
  • Only statistically significant p values are described. CIMP, CpG island methylator phenotype; LOH, loss of heterozygosity; MSI, microsatellite instability; MSS, microsatellite stable.