Neuronal differentiation, egfr over-expression and EGFR gene amplification in glioblastomas and the relationship of these parameters between each other and prognosis

AIM: The aim of this study is to state both neuronal differentiation and epidermal growth factor receptor (EGFR) over expression/amplification in primary glioblastomas (GB) and find out any relationship between these parameters, as well as with age and sex, tumor localization, method of operation, Ki-67 status, treatment modalities and survival.MATERIALS AND METHODS: Fifty-two primary glioblastoma cases were evaluated for neuronal differentiation by using neurofilament protein (NFP) and synaptophysin. Immunoreactivity was assessed by scoring the intensity of staining and ratio of the stained cells. Immunoreactivity for another neuronal marker, neuronal nuclear antigen (Neu-N) was reviewed in obviously tumoral cells together with glial fibrillary asidic protein (GFAP), by dual immunohistochemistry (IHC) method. Again with IHC, EGFR over-expression and Ki-67 status were stated. EGFR gene amplification was explored by dual EGFR- silver in situ hibridization (SISH)/ chromosome 7-chromogen in situ hibridization method.RESULTS: Negative correlation was found between age and survival (p=0.001), while expressions of NFP-synaptophysin (p=0.000); NFP-Neu-N (p=0.002); synaptophysin-Neu-N (p=0.015); Neu-N expression-EGFR amplification (p=0.012); EGFR over-expression-EGFR amplification (p=0.001) and EGFR amplification-frontal lobe localization (p=0.006) were pozitively correlated. Patients who received radiotherapy, chemotherapy and temozolamide together, were found to have a longer life-time than others received radiotherapy alone (p=0.006). Also, the probability to have a life-time more than 18 months were found significantly higher in patients showing EGFR amplification and suffering a frontal lobe tumor p=0.018, p= 0,018, respectively). No statistically significant relationship was found between either neuronal differentiation and survival or other parameters assessed.CONCLUSIONS: The results of the study highlight that long-term survival in primary GB may be related with EGFR amplification but not with neuronal differentiation. The stated correlation between Neu-N expression and EGFR amplification was not reflected to survival statistics and remains to be an issue for new and larger series.