Immunohistochemical detection of epidermal growth factor receptor in human high-grade astrocytomas--a comparison between frozen- and paraffin sections

Abstract

The overexpression of epidermal growth factor receptor (EGFR) in human astrocytic tumours is associated with the oncogenesis of these tumours. Ongoing research on diagnostic, prognostic, and therapeutic aspects of this receptor is highly dependent on the development of reliable techniques for the detection of EGFR in tumour tissue. The aim of this study was to assess EGFR expression in human high-grade astrocytomas by means of immunohistochemistry on formalin-fixed, paraffin-embedded sections and to compare these findings with the results of our previous study on frozen sections from these tumours, in which we found about 60% EGFR positivity (10). Four anaplastic astrocytomas and 19 glioblastomas were included in this study. Two different antibodies were used, the monoclonal antibody E30 reactive against the extracellular domain of EGFR and the polyclonal antibody Ab-4 directed against its cytoplasmic domain. With E30, 3 out of 4 anaplastic astrocytomas (75%) and 12 out of 19 glioblastomas (63%) were found to express EGFR whereas Ab-4 demonstrated positive EGFR immunoreactivity in most of the tumours (18/19 glioblastomas and all the 4 anaplastic astrocytomas). In conclusion, immunohistochemistry represents a reliable and convenient technique for the detection of EGFR in tissue sections of human high-grade astrocytomas, and that EGFR immunoreactivity is comparable in frozen- and paraffin sections from these tumours.