Analysis of prognosis of high grade gliomas in the view of new immunohistochemistry markers and 2016 WHO classification

INTRODUCTION: During studies over pathophysiology of gliomas, these tumors are found to have several diagnostic markers, which are included in the WHO Classification in 2016. In our study, we aimed to study IDH mutation and Ki 67 index and therefore investigate whether these markers effected the initial diagnosis and survival rates. METHOD: High grade glioma patients,who were operated in our department between 2013 and 2018, were retrospectively reviewed. New immunohistochemistry staining studies were conducted and survival analyses were done. RESULTS: Out of 135 patients and 136 tumor, among previous diagnosis, there were 117 (%86) GBMs, eight (%6) grade III-IV gliomas, four (%3) anaplastic astrocytomas and seven (%5) anaplastic oligodendrogliomas. One patient had both GBM and anaplastic astrocytoma as two distinct lesions. Mean age was 55 (7-85). 88 (%65) were male and 47 (%35) were female. 14 patients were reoperated due to recurrence, out of these patients two patients' diagnosis upgraded. Most common complaint was motor deficit (%56). Statistics about tumor location showed that there were 53 (%39) frontal, 39 (%29) temporal, 16 (%12) parietal, four (%3) occipital, five (%4) insular, eight (%6) corpus callosum, six (%4) thalamus, one (%0.5) cerebellar, two (%1) intraventricular and one (%0.5) septum pellucidum tumor. MR features showed that necrosis is statistically related to GBM. (p < 0.01) 126 patients (%93.3) were IDH wildtype and 9 (%6.7) were mutant. This information changed the diagnosis of six patients to GBM, IDH wildtype , who were previously diagnosed as grade III-IV glioma. Five patients, even though they were initially diagnosed with anaplastic astrocytoma and anaplastic oligodendroglioma, are found to be IDH wildtype. IDH mutation, extend of resection and age are found to be effective on survival. CONCLUSION: High grade gliomas were classified as IDH mutant and IDH wildtype tumors following new classification. These groups showed difference in survival rates. Also IDH mutation was found to be related to several radiologic features of tumors. Extend of resection had profound effect on survival. Detailing the diagnosis with molecular features will help clinicians to plan specific adjuvant therapies, which leads survival rates to increase.