Rapid Detection of high-level oncogene amplifications in ultrasonic surgical aspirations of brain tumors

Diagnostic Pathology

Table 3 FISH versus MLPA results for EGFR

Tumor	EGFR/CEP 7 ratios in FISH assays on FFPE		EGFR’s tumor/NB DNA ratios (normalized CN) Average of 2 MLPA probe sets ± SD
	Total EGFR/ Total CEP 7 signals	Median ratio	CUSA	FFPE
GBM1	7.3	7.2	8.8 ± 0.2	21.1 ± 2.0
GBM2	8.6	9.3	22.5 ± 7.9	19.3 ± 7.2
GBM3	10.3	9.0	10.5 ± 3.8	33.1 ± 17.2
GBM4	11.1	11.6	19.5 ± 9.3	26.7 ± 6.5
LCM1	1.0	1.0	1.2 ± 0.5	1.2 ± 0.4
LCM2	1.1	1.0	2.3 ± 0.9	2.3 ± 1.4
EP1	1.0	1.0	1.7 ± 0.7	2.9 ± 2.6

Although amplification of EGFR seen in individual cells of GBMs varied greatly and MLPA provided collective results of numerous cells, both techniques demonstrated corresponding large elevations in copy number for this oncogene in GBMs. Polysomy may have accounted for low-level amplifications found with MLPA in LCM2 and EP1. Median ratios were derived from the distributions of signal ratios in individual cells. EGFR = Epidermal Growth Factor Receptor. CEP 7 = Centromere of chromosome 7, FISH = Fluorescence in situ hybridization. SD = Standard deviation. CUSA = Cavitronic ultrasonic surgical aspiration. FFPE = Formalin-fixed, paraffin embedded tissue.

ISSN: 1746-1596