Multicentric Low-Grade Gliomas

Multicentric Glioma: An Ideal Model to Reveal the Mechanism of Glioma

As a special type of glioma, multicentric glioma provides an ideal pathological model for glioma research. According to the stem-cell-origin theory, multiple lesions of multicentric glioma share the same neuro-oncological origin, both in gene level and in cell level. Although the number of studies focusing on genetic evolution in gliomas with the model of multicentric gliomas were limited, some mutations, including IDH1 mutations, TERTp mutations and PTEN deletions, are found to be at an early stage in the process of genetic aberrance during glioma evolution based on the results of these studies. This article reviews the clinical reports and genetic studies of multicentric glioma, and intends to explain the various clinical phenomena of multicentric glioma from the perspective of genetic aberrance accumulation and tumor cell evolution. The malignant degree of a glioma is determined by both the tumorigenicity of early mutant genes, and the stemness of early suffered cells.

Is It Worth Considering Multicentric High-Grade Glioma a Surgical Disease? Analysis of Our Clinical Experience and Literature Review

INTRODUCTION

The simultaneous presence of multiple foci of high-grade glioma is a rare condition with a poor prognosis. By definition, if an anatomical connection through white matter bundles cannot be hypothesized, multiple lesions are defined as multicentric glioma (MC); on the other hand, when this connection exists, it is better defined as multifocal glioma (MF). Whether surgery can be advantageous for these patients has not been established yet. The aim of our study was to critically review our experience and to compare it to the existing literature.

MATERIALS AND METHODS

Retrospective analysis of patients operated on for MC HGG in two Italian institutions was performed. Distinction between MC and MF was achieved through revision of MR FLAIR images. Clinical and radiological preoperative and postoperative data were analyzed through chart revision and phone interviews. The same data were extracted from literature review. Univariate and multivariate analyses were conducted for the literature review only, and the null hypothesis was rejected for a p-value ≥ 0.05.

RESULTS

Sixteen patients met the inclusion criteria; male predominance and an average age of 66.5 years were detected. Sensory/motor deficit was the main onset symptom both in clinical study and literature review. A tendency to operate on the largest symptomatic lesion was reported and GTR was reached in the majority of cases. GBM was the histological diagnosis in most part of the patients. OS was 8.7 months in our series compared to 7.5 months from the literature review. Age ≤ 70 years, a postoperative KPS ≥ 70, a GTR/STR, a second surgery and adjuvant treatment were shown to be significantly associated with a better prognosis. Pathological examination revealed that MC HGG did not originate by LGG.

CONCLUSIONS

MC gliomas are rare conditions with high malignancy and a poor prognosis. A maximal safe resection should be attempted whenever possible, especially in younger patients with life-threatening large mass.

Dissemination Patterns and Short-Term Management of Multifocal Rosette-Forming Glioneuronal Tumors

BACKGROUND

Multifocal rosette-forming glioneuronal tumors (RGNTs) are challenging to manage. Gross total resection is often impossible, and data on adjunctive therapies are limited. We reviewed cases of multifocal RGNTs in the literature with special focus on dissemination patterns and management.

METHODS

A literature review was conducted using PubMed and the key words "(multifocal OR multicentric OR satellite OR dissemination) AND glioneuronal."

RESULTS

There were 21 cases of multifocal RGNTs identified. Follow-up was available in 18 cases at a median of 17 months. Progression-free survival and overall survival at 1 year were 84% and 94%, respectively. Of all cases, 43% had cerebrospinal fluid (CSF) dissemination, 48% had intraparenchymal spread, and 10% had both. The presence of CSF dissemination led to palliative care and/or death in 20% of cases (n = 2). None of the cases with intraparenchymal spread progressed. Radiotherapy was used in 50% of cases with CSF dissemination, chemotherapy was used in 20%, and CSF shunting was used in 36%. No tumors with intraparenchymal spread required adjunctive therapy or shunting.

CONCLUSIONS

RGNTs with CSF dissemination are more likely to behave aggressively, and early adjunctive therapies should be discussed with patients. Tumors with intraparenchymal spread grow slowly, and maximal safe resection followed by observation is likely sufficient in the short term. Long-term behavior of multifocal RGNTs is still unclear.

An Integrative Survival Analysis for Multicentric Low-Grade Glioma

OBJECTIVE

This study aimed to perform a survival analysis of patients with multicentric low-grade gliomas (MLGGs) and to assess the influence of various prognostic factors on progression-free survival (PFS) and overall survival.

METHODS

A literature search on Web of Science and PubMed was performed for literature in English published from 1963 to September 2018. Detailed information including demographics, clinical characteristics, treatments, critical events, and time to events for survival analysis were extracted from the included articles.

RESULTS

A total of 36 cases from published articles were selected for analysis. Univariate analysis showed that age (<31 years or ≥31 years), grade (pure low grade/low and high grade) and glioma type (astrocytoma/oligodendroglioma) had a significant relationship with PFS. Cox regression analysis showed that tumor grade was an independent prognostic factor for PFS. No factors correlated with overall survival.

CONCLUSIONS

This integrative analysis of MLGGs patients revealed that age younger than 31 years, pure MLGG, and oligodendroglioma were significantly associated with improved PFS, and pure MLGGs was an independent prognostic factors for PFS.

Genomic analysis of the origins and evolution of multicentric diffuse lower-grade gliomas

Background

Rare multicentric lower-grade gliomas (LGGs) represent a unique opportunity to study the heterogeneity among distinct tumor foci in a single patient and to infer their origins and parallel patterns of evolution.

Methods

In this study, we integrate clinical features, histology, and immunohistochemistry for 4 patients with multicentric LGG, arising both synchronously and metachronously. For 3 patients we analyze the phylogeny of the lesions using exome sequencing, including one case with a total of 8 samples from the 2 lesions.

Results

One patient was diagnosed with multicentric isocitrate dehydrogenase 1 (IDH1) mutated diffuse astrocytomas harboring distinct IDH1 mutations, R132H and R132C; the latter mutation has been associated with Li-Fraumeni syndrome, which was subsequently confirmed in the patient's germline DNA and shown in additional cases with The Cancer Genome Atlas data. In another patient, phylogenetic analysis of synchronously arising grade II and grade III diffuse astrocytomas demonstrated a single shared mutation, IDH1 R132H, and revealed convergent evolution via non-overlapping mutations in ATRX and TP53. In 2 cases, there was divergent evolution of IDH1-mutated and 1p/19q-codeleted oligodendroglioma and IDH1-mutated and 1p/19q-intact diffuse astrocytoma, occurring synchronously in one case and metachronously in a second.

Conclusions

Each tumor in multicentric LGG cases may arise independently or may diverge very early in their development, presenting as genetically and histologically distinct tumors. Comprehensive sampling of these lesions can therefore significantly alter diagnosis and management. Additionally, somatic IDH1 R132C mutation in either multicentric or solitary LGG identifies unsuspected germline TP53 mutation, validating the limited number of published cases.