Epidermal Growth Factor Receptor Expression Predicts Time and Patterns of Recurrence in Patients with Glioblastoma After Radiotherapy and Temozolomide.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the potential role of epidermal growth factor receptor (EGFR) protein expression in predicting the modality of treatment failure in glioblastoma (GB).

METHODS: Patients with unifocal GB undergoing surgery and postoperative radiochemotherapy 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 and low expression. Time to progression (TTP) and pattern of recurrence (PR) were evaluated. PRs were classified as central, in-field, marginal, or distant recurrences.

RESULTS: After a median follow-up time of 13 months (range, 6-67 months), 102 patients (79.1%) showed recurrences that were detectable on magnetic resonance imaging. Median TTP was 9 months after the completion of radiochemotherapy. EGFR expression was significantly correlated with TTP (log-rank test, P = 0.003) and PR (Fisher exact test, P = 0.01). The low-EGFR group had a median TTP of 13 months and a prevalence of central/in-field recurrences (accounting to a total 81%). The high-EGFR group had a shorter median TTP (6 months) and a higher rate of marginal/distant recurrences (55.6%).

CONCLUSIONS: Different modality of recurrence related to EGFR expression in patients with GB envisages implication for target contouring of radiotherapy volumes and other therapeutic strategies.