Glioma imaging in Europe: A survey of 220 centres and recommendations for best clinical practice

Objectives: At a European Society of Neuroradiology (ESNR) Annual Meeting 2015 workshop, commonalities in practice, current controversies and technical hurdles in glioma MRI were discussed. We aimed to formulate guidance on MRI of glioma and determine its feasibility, by seeking information on glioma imaging practices from the European Neuroradiology community. Methods: Invitations to a structured survey were emailed to ESNR members (n=1,662) and associates (n=6,400), European national radiologists’ societies and distributed via social media. Results: Responses were received from 220 institutions (59% academic). Conventional imaging protocols generally include T2w, T2-FLAIR, DWI, and pre- and post-contrast T1w. Perfusion MRI is used widely (85.5%), while spectroscopy seems reserved for specific indications. Reasons for omitting advanced imaging modalities include lack of facility/software, time constraints and no requests. Early postoperative MRI is routinely carried out by 74% within 24–72 h, but only 17% report a percent measure of resection. For follow-up, most sites (60%) issue qualitative reports, while 27% report an assessment according to the RANO criteria. A minori

MAPK pathway activation in pilocytic astrocytoma

Pilocytic astrocytoma (PA) is the most common tumor of the pediatric central nervous system (CNS). A body of research over recent years has demonstrated a key role for mitogen-activated protein kinase (MAPK) pathway signaling in the development and behavior of PAs. Several mechanisms lead to activation of this pathway in PA, mostly in a mutually exclusive manner, with constitutive BRAF kinase activation subsequent to gene fusion being the most frequent. The high specificity of this fusion to PA when compared with other CNS tumors has diagnostic utility. In addition, the frequency of alteration of this key pathway provides an opportunity for molecularly targeted therapy in this tumor. Here, we review the current knowledge on mechanisms of MAPK activation in PA and some of the downstream consequences of this activation, which are now starting to be elucidated both in vitro and in vivo, as well as clinical considerations and possible future directions

DNA methylation-based classification of central nervous system tumours.

Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology

Biology and grading of pleomorphic xanthoastrocytoma: what have we learned about it?

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytoma predominantly affecting children and young adults. We performed comprehensive genomic characterization on a cohort of 67 patients with histologically defined PXA (n = 53, 79%) or anaplastic PXA (A-PXA, n = 14, 21%), including copy number analysis (ThermoFisher Oncoscan, n = 67), methylation profiling (Illumina EPIC array, n = 43) and targeted next generation sequencing (n = 32). The most frequent alterations wereCDKN2A/Bdeletion (n = 63; 94%) andBRAFp.V600E (n = 51, 76.1%). In 7BRAFp.V600 wild-type cases, alternative driver alterations were identified involvingBRAF,RAF1andNF1. Downstream phosphorylation of ERK kinase was uniformly present. Additional pathogenic alterations were rare, withTERT,ATRXandTP53mutations identified in a small number of tumors, predominantly A-PXA. Methylation-based classification of 46 cases utilizing a comprehensive reference tumor allowed assignment to the PXA methylation class in 40 cases. A minority grouped with the methylation classes of ganglioglioma or pilocytic astrocytoma (n = 2), anaplastic pilocytic astrocytoma (n = 2) or control tissues (n = 2). In 9 cases, tissue was available from matched primary and recurrent tumors, including 8 with anaplastic transformation. At recurrence, two tumors acquiredTERTpromoter mutations and the majority demonstrated additional non-recurrent copy number alterations. Methylation class was preserved at recurrence. For 62 patients (92.5%), clinical follow-up data were available (median follow-up, 5.4 years). Overall survival was significantly different between PXA and A-PXA (5-year OS 80.8% vs. 47.6%;P = 0.0009) but not progression-free survival (5-year PFS 59.9% vs. 39.8%;P = 0.05). WHO grade remained a strong predictor of overall survival when limited to 38 cases defined as PXA by methylation-based classification. Our data confirm the importance of WHO grading in histologically and epigenetically defined PXA. Methylation-based classification may be helpful in cases with ambiguous morphology, but is largely confirmatory in PXA with well-defined morphology

Management of Primary Tectal Plate Low-Grade Glioma in Pediatric Patients: Results of the Multicenter Treatment Study SIOP-LGG 2004

Background Tectal plate low-grade gliomas (LGGs) most often present with increased intracranial pressure and sometimes as incidental findings from brain imaging. Prognostic factors predicting outcome are largely unknown. Methods  From 2004 until 2012, 71 patients with tectal plate LGG from Germany and Switzerland were followed within the SIOP-LGG 2004 study. Median age at diagnosis was 9.7 (range: 0.1–17.5) years, and median follow-up time of surviving patients was 6.3 (interquartile range: 4.9–8.3) years. Results  A total of 41 out of 71 patients received no tumor treatment (12 with and 29 without biopsy). The 10-year event-free survival (EFS) rate (± standard error ) for patients with an initial tumor volume of ≤3 cm3 was 56% (±7%), as opposed to 12% (±8%) for those with tumors >3 cm3 (p < 0.001). The 10-year EFS for patients without contrast enhancement on initial magnetic resonance imaging (MRI) was 52% (±9%), and for those with enhancement, it was 23% (±9%) (p = 0.003). The 10-year overall survival rate was 96% (±3%) (death due to disease, 1; ventriculoperitoneal shunt infection, 1). Sixty-three (89%) patients had at least one cerebrospinal fluid diversion procedure. Conclusions More than half of patients were managed without tumor treatment. Favorable prognostic factors for EFS were small initial tumor volume (≤3cm3) and the absence of initial contrast enhancement on MRI. Overall survival was excellent

A multivariate analysis of factors determining tumor progression in childhood low-grade glioma: a population-based cohort study (CCLG CNS9702)

The purpose of this study was to identify risk factors for the progression of low-grade glioma in children from a large population-based cohort. Patient and tumor details of a national cohort of children with low-grade glioma, recruited into an international multidisciplinary clinical strategy, were subjected to univariate and multivariate analyses of progression-free survival and overall survival. From the cohort of 798 patients, 639 patients were eligible, with a median age 6.71 years (0.26–16.75 years); 49% were males; 15.9% had neurofibromatosis type 1, 63.7% pilocytic astrocytoma, 5.9% fibrillary astrocytoma, 4.2% mixed neuronal-glial tumors, and 3.6% others; 21.1% were diagnosed clinically. Anatomically implicated were 31.6% cerebellum, 24.6% chiasma/hypothalamus, 16.0% cerebral hemispheres, 9.9% brain stem, 6.1% other supratentorial midline structures, 5.9% optic nerve only, 4.5% spinal cord, and 1.4% others. The 5-year overall survival and progression-free survival in the whole cohort were 94.6% and 69.4%, respectively. There was a significant association between age and site (P < .001) and extent of tumor resection and site (P < .001). Multivariate analysis identified young age, fibrillary astrocytoma, and extent of surgical resection as significant independent risk factors for progression. Hypothalamic/chiasmatic tumors demonstrated the most sustained tendency to progress. In conclusion, the influence of age and anatomical site upon the risk of tumor progression suggests that these factors strongly influence tumor behavior for the majority of pilocytic tumors. Age <1 year and 1–5 years, fibrillary histology, completeness of resection, and chiasmatic location are candidates for stratification in future studies