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 2 Cases

case ID	type	LI	SL	MLPA	MLPA 0-3	MLPA >0.25	DL
1	oligo	7.567	1	0.6275	2	1	1
2	oligo	13.700	1	0.675	2	1	1
3	oligo	12.600	1	0.8075	3	1	1
4	oligo	24.667	1	0.4725	1	1	1
5	oligo	17.100	1	0.8525	3	1	1
6	oligo	13.600	1	0.8025	3	1	1
7	oligo	19.567	1	0.6425	2	1	1
8	oligo	14.267	1	0.6925	2	1	1
9	oligo	8.800	1	0.6525	2	1	1
10	oligo	26.133	1	0.5925	2	1	*1
11	gbm	56.367	0	0.1125	0	0	0
12	gbm	19.167	1	0.8475	3	1	1
13	gbm	84.400	0	0.09	0	0	0
14	gbm	17.967	1	0.2625	1	1	*1
15	gbm	57.700	0	0.255	1	1	0
16	gbm	89.900	0	0.4075	1	1	0
17	gbm	72.267	0	0.2075	0	0	0
18	gbm	19.533	1	0.3525	1	1	*1
19	gbm	54.133	0	0.42	1	1	*1
20	gbm	53.900	0	0.1375	0	0	0
21	gbm	21.967	1	0.485	1	1	1
22	gbm	54.167	0	0.5475	2	1	1
23	gbm	33.000	1	0.085	0	0	0
24	gbm	76.300	0	0.2725	1	1	0
25	gbm	96.733	0	0.24	0	0	0
26	gbm	49.567	1	0.4275	1	1	1
27	gbm	43.967	1	0.1375	0	0	*1
28	gbm	40.533	1	0.1025	0	0	0
29	gbm	7.233	1	0.1275	0	0	1
30	gbm	39.067	1	0.5125	2	1	1
31	gbm	25.833	1	0.2075	0	0	*1
32	gbm	33.900	1	0.13	0	0	*1
33	gbm	28.000	1	0.365	1	1	0
34	gbm	45.000	1	0.275	1	1	1
35	gbm	84.100	0	0.205	0	0	0
36	gbm	85.100	0	0.2975	1	1	0
37	gbm	64.933	0	0.11	0	0	0
38	gbm	53.400	0	0.17	0	0	0
39	gbm	6.800	1	0.825	3	1	1
40	gbm	22.500	1	0.2425	0	0	0

Case ID (identification) is the case number we assigned in this study. Tumour types were oligodendroglial tumours (oligo) and glioblastomas (gbm). The oligodendroglial tumours were oligodendroglioma WHO grade II (cases 4, 5 and 6), anaplastic oligodendroglioma WHO grade III (cases 1, 2, 3, 7 and 9), oligoastrocytoma WHO grade II (case 10) and anaplastic oligoastrocytoma WHO grade III (case 8). The glioblastomas were all glioblastoma WHO grade IV except cases 13 and 18 which were glioblastoma with oligodendroglioma component WHO grade IV. LI is the nuclear labelling index for single-labelled MGMT as determined by computerised image analysis. SL is the binarised score for the single-labelling (0 = LI > 50%, 1 = LI from 0 to 50%). MLPA is the MLPA ratio (please see text). MLPA 0–3 is the score for MLPA according to cut-offs for the MLPA ratio provided by Jeuken et al. 2007 [10] (0 = unmethylated, 1 = mildly methylated, 2 = moderately methylated and 3 = extensively methylated). MLPA > 0.25 is the binarised methylation score for MLPA (0 = unmethylated, 1 =methylated). DL is the binarised score for double labelling (0 = mainly MGMT-positive in tumour cells, 1 = mainly MGMT-negative in tumour cells). The asterisked cases were initially assigned a score of 1 in the tripartite system (please see text for explanation).

ISSN: 2051-5960