Expression of EGFR in Paired New and Recurrent Glioblastomas

Background: The aim of this study was to analyse the expression of EGFR in newly diagnosed and recurrent glioblastoma multiforme (GBM). Materials and Methods: Our study included a total of 48 paired samples collected from 24 patients diagnosed with GBM. The intensity of EGFR cytoplasmatic staining was scored on a scale of 1-3 (weak, intermediate or strong). Results: We found EGFR overexpression in 23 patients (96%) with newly diagnosed GBM, while all recurrent tumours overexpressed EGFR. Ten recurrent tumours (42%) had a lower expression than their new counterpart 13 tumours (54%) had a similar expression, and only one case (2%) had increased expression on recurrence. The expression of EGFR in newly diagnosed GBM was significantly correlated with EGFR expression in recurrent tumour (p 0.036). In addition, new GBMs with strong EGFR expression had a mean relapse-free interval of 11.5 months (p0.017). A benefit of combined therapy was observed in the radiotherapy-plus-chemotherapy group where the average time was 11 months (p0.011), as compared with surgery/radiotherapy alone (average time 6.8 months). Conclusions: The present data show that EGFR is overexpressed in paired GBMs. The discrepancies of EGFR expression between the primary tumour and the recurrence suggest heterogeneity of GBMs but also unity at relapse.