Epidermal Growth Factor Receptor Expression predicts Time and Patterns of Recurrence in Glioblastoma Patients Following Radiotherapy and Temozolomide.

BACKGROUND: and Purpose: The aim is to investigate the potential role of EGFR protein expression in predicting the modality of treatment failure in Glioblastoma (GB). MATERIAL AND METHOD: Patients with unifocal GB undergoing surgery and postoperative radio-chemotherapy (RT-TMZ) from February 2008 to July 2015 were included into the study. The EGFR protein expression level was assessed by immunohistochemistry in GB tissues and classified into High (H-EGFR) and Low (L-EGFR) expression. Time-to-progression (TTP) and pattern of recurrence (PR) were evaluated. PRs were classified in: central (C), in-field (I-F), marginal (M) or distant (D) recurrences. RESULTS: After a median follow-up time of 13 months (range: 6-67 months), 102 patients (79,1%) showed MRI-detectable recurrences. Median TTP was 9 months after the completion of RT-TMZ. EGFR expression was significantly correlated with TTP (log-rank test: p= 0.003) and PR (Fisher's exact test: p=0,01). L-EGFR group had a median TTP of 13 months and a prevalence of C/I-F recurrences (accounting to a total 81%). H-EGFR group had a shorter median TTP (6 months) and a higher rate of M/D recurrences (55,6%), CONCLUSIONS: Different modality of recurrence related to EGFR expression in GB patients envisages implication for target contouring of RT volumes and other therapeutic strategies