Diagnostic implications of TERT promoter mutation status in diffuse gliomas in a routine clinical setting

TERT Promoter Alterations in Glioblastoma: A Systematic Review

Simple Summary

Glioblastoma is the most common malignant primary brain tumor in adults. Glioblastoma accounts for 2 to 3 cases per 100,000 persons in North America and Europe. Glioblastoma classification is now based on histopathological and molecular features including isocitrate dehydrogenase (IDH) mutations. At the end of the 2000s, genome-wide sequencing of glioblastoma identified recurrent somatic genetic alterations involved in oncogenesis. Among them, the alterations in the promoter region of the telomerase reverse transcriptase (TERTp) gene are highly recurrent and occur in 70% to 80% of all glioblastomas, including glioblastoma IDH wild type and glioblastoma IDH mutated. This review focuses on recent advances related to physiopathological mechanisms, diagnosis, and clinical implications.

Abstract

Glioblastoma, the most frequent and aggressive primary malignant tumor, often presents with alterations in the telomerase reverse transcriptase promoter. Telomerase is responsible for the maintenance of telomere length to avoid cell death. Telomere lengthening is required for cancer cell survival and has led to the investigation of telomerase activity as a potential mechanism that enables cancer growth. The aim of this systematic review is to provide an overview of the available data concerning TERT alterations and glioblastoma in terms of incidence, physiopathological understanding, and potential therapeutic implications.

Adult Diffuse Astrocytic and Oligodendroglial Tumors

Infiltrating gliomas comprise the most common group of primary intraparenchymal brain tumors and present a level of complexity which requires careful integration of histopathology and molecular diagnostics for optimal therapy. To this end, the fourth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) has been followed by a series of publications by cIMPACT-NOW (the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy) incorporating molecular signatures to propose updated diagnostic categories in anticipation of the upcoming fifth edition of CNS tumor classification. Integration of histopathology, immunophenotyping, and molecular findings is profoundly changing the practice of diagnostic surgical neuropathology and enabling a more personalized approach to treating patients with gliomas.

Preoperative Neutrophil/Lymphocyte Ratio Is an Independent Prognostic Biomarker in Patients with Low-Grade Gliomas

BACKGROUND

There are no standardized criteria to predict the prognosis of patients with low-grade gliomas. Therefore, novel prognostic biomarkers that can guide follow-up schedules and therapeutic approaches urgently are required in patients with low-grade gliomas.

METHODS

One hundred nineteen patients with World Health Organization (WHO) II gliomas were recruited between January 2010 and December 2016 from Xiangya Hospital for this study. We collected neutrophil and lymphocyte values from the full blood counts measured 24 h before surgery. Neutrophil-to-lymphocyte ratios (NLRs) were then calculated. The significance of the NLR was determined based on a nonparametric test. The Kaplan-Meier method was used to estimate survival rates. The influence of the NLR on progression-free survival and overall survival was evaluated using univariate and multivariate Cox proportional hazards models.

RESULTS

Preoperative NLRs were upregulated in patients with WHO II gliomas who relapsed or died. Preoperative NLRs were also significantly correlated with age, preoperative neutrophil values, and preoperative lymphocyte values. Compared with the low preoperative NLR group, patients with WHO II gliomas in the high preoperative NLR group had significantly higher relapse and lower survival rates. In addition, the preoperative NLR and tumor type were independent prognostic parameters of progression-free survival for WHO II gliomas, whereas only the preoperative NLR was an independent prognostic parameter of overall survival for WHO II gliomas.

CONCLUSIONS

High preoperative NLRs were significantly associated with greater relapse and poor prognosis in patients with WHO II gliomas.

Genetic Abnormalities, Clonal Evolution, and Cancer Stem Cells of Brain Tumors

Brain tumors are highly heterogeneous and have been classified by the World Health Organization in various histological and molecular subtypes. Gliomas have been classified as ranging from low-grade astrocytomas and oligodendrogliomas to high-grade astrocytomas or glioblastomas. These tumors are characterized by a peculiar pattern of genetic alterations. Pediatric high-grade gliomas are histologically indistinguishable from adult glioblastomas, but they are considered distinct from adult glioblastomas because they possess a different spectrum of driver mutations (genes encoding histones H3.3 and H3.1). Medulloblastomas, the most frequent pediatric brain tumors, are considered to be of embryonic derivation and are currently subdivided into distinct subgroups depending on histological features and genetic profiling. There is emerging evidence that brain tumors are maintained by a special neural or glial stem cell-like population that self-renews and gives rise to differentiated progeny. In many instances, the prognosis of the majority of brain tumors remains negative and there is hope that the new acquisition of information on the molecular and cellular bases of these tumors will be translated in the development of new, more active treatments.