Kim Phipps

Management of choroid plexus tumours in children : 20 years experience at a Single Neurosurgical Centre

Objective: Tumours of the choroid plexus are rare tumours of neuro-ectodermal origin, accounting for less than 1% of all intracranial tumours. Most cases present in children less than 2 years of age. While choroid plexus carcinomas (CPC) are reported to have an extremely poor prognosis, choroid plexus papillomas (CPP) are generally regarded as benign tumours with a very favourable long-term outcome. Management dilemmas are associated with the choice of surgical procedure, tumour vascularity, the treatment of hydrocephalus and the value of adjuvant therapy. The objective of this study was to review our experience with this rare tumour over a 20-year period. Methods: Patients were identified from the Great Ormond Street Neurosurgical Brain Tumour Database. Over a 20-year period (1979–1999), 34 children were identified with a choroid plexus tumour. There were 25 cases of CPP and 9 cases of CPC. A retrospective review of case notes, radiological imaging, operation reports and pathology was performed. Results: The median age at presentation was 17 months (1–138) for CPP and 13 months (2–102) for CPC. There was no sex difference for CPP. However, 8 of the 9 CPCs were male (89%). A complete surgical resection was achieved in all 25 cases of CPP and in 3 cases of CPC (33%). The median survival for CPPs was 75.5 months (2–228), with a median follow-up of 73.5 months (2–228). The median survival for CPCs was 6 months (1–90), with a median follow-up of 6 months (1–90). Conclusion: With modern neurosurgical practise, a cure should be the aim for all children with CPP. There is no evidence that adjuvant therapy has any role in the primary management of these children. However, CPC still has an extremely poor prognosis, and the efficacy of adjuvant therapy remains to be established.

Craniopharyngioma in childhood : our evidence-based approach to management

ObjectivesIn 1996 we published our results for treatment of childhood craniopharyngioma. That study did not only reveal that there was a significant morbidity associated with our then policy of attempted radical removal followed by post-operative radiotherapy in those cases with residual disease, but also that risk factors for poor outcome could be identified based on the clinical and radiological findings at presentation. As result of that study, we redefined the role of radical surgery in the treatment of craniopharyngioma and developed a new treatment strategy in an attempt to improve the quality of outcome without compromising tumour control. Our aims in this paper were to compare the results of our current treatment strategy with that reported in the 1996 paper to assess whether we have achieved this goal.MethodsA detailed assessment of the treatment pathway and outcome was undertaken for children treated for craniopharyngioma in our unit from 1996 to 2004. This included a morbidity score based on visual, motor, cognitive, hypothalamic and endocrinological data obtained from our neuro-oncology database and review of clinical records. Where possible we have attempted to record data in the same manner as for our previous study allowing for meaningful comparison.ResultsForty-eight children with craniopharyngioma presented in the study period. On the basis of clinical presentation and radiological findings, 25 were deemed suitable for attempted radical surgery and 23 were treated with various subtotal surgical procedures. Radiotherapy was used in patients over the age of 5 years where residual tumour was present or progressed after the initial surgical intervention(s). Morbidity scores, particularly in relation to visual and cognitive outcome, are improved and there was no surgical mortality in the current series.ConclusionsA treatment paradigm for childhood craniopharyngioma is presented which improves the quality of outcome without compromising tumour control.

RAF gene fusions are specific to pilocytic astrocytoma in a broad paediatric brain tumour cohort

Brain tumours are the most common solid tumour in children and are the primary cause of cancer-related death in children and young adults [4, 6]. The most prevalent childhood brain tumours are low-grade gliomas, specifically pilocytic astrocytomas (PAs, WHO Grade I) [1]. PAs are slow-growing tumours which are often cystic, and may occur sporadically or in association with the genetic disorder Neurofibromatosis type 1. Several recent studies including our own have identified novel KIAA1549–BRAF and SRGAP3–RAF1 gene fusions in the majority of PAs tested [3, 7, 8, 12]. In these fusions, the N-terminal autoinhibitory domains of the RAF proteins are replaced by those of KIAA1549 or SRGAP3, resulting in constitutive activation of the ERK/MAPK pathway. A recent study has suggested that the KIAA1549–BRAF fusion is more common in PAs originating in the cerebellum [5]. In low-grade glioma without RAF gene fusions there is increasing evidence for activation of the ERK/MAPK pathway through alternative mechanisms, such as point mutation of KRAS or BRAF [2, 11, 13]. Despite the high frequency of RAF gene fusions in PAs, they have not been investigated in other types of paediatric brain tumours. In this study, we screened a new cohort of 74 paediatric brain tumours, with a range of different pathologies, for all known KIAA1549–BRAF and SRGAP3–RAF1 fusion variants. Access to tumours and clinical data was in accordance with Local Research Ethics Committee (LREC) regulations: Great Ormond Street Hospital LREC reference number 05/Q0508/153. Tumours were classified by diagnostic criteria defined by the World Health Organization (WHO) [10]. Total RNA was extracted from fresh frozen tissue samples using the miRNeasy mini kit (Qiagen, Crawley, UK) and reverse transcribed using the SuperScript First-Strand cDNA synthesis system (Invitrogen, Carlsbad, CA). KIAA1549–BRAF fusions were detected using previously described primers and techniques [3]. The primers used for detecting SRGAP3–RAF1 fusions were 50-TGG CAGTAACCTCATCACCA-30 (located in SRGAP3 exon 10) and 50-GGTTGGGTCGACAACCTTTA-30 (located in RAF1 exon 11). All fusions identified by PCR were confirmed by direct sequencing on a 3100 Genetic Analyzer capillary sequencer (Applied Biosystems, Foster City, CA). Electronic supplementary material The online version of this article (doi:10.1007/s00401-010-0693-y) contains supplementary material, which is available to authorized users.

Neuroendocrine Morbidity After Pediatric Optic Gliomas: A Longitudinal Analysis of 166 Children Over 30 Years

CONTEXT Fifty percent of pediatric low-grade gliomas affect the optic pathway, hypothalamus, and suprasellar areas (OP/HSGs), resulting in significant long-term neuroendocrinopathy. OBJECTIVE This study aimed to dissect tumor- from treatment-related risk factors for OP/HSG-associated neuroendocrinopathy. DESIGN This was a retrospective case notes analysis of 166 children with newly diagnosed OP/HSGs at our quaternary center between 1980 and 2010 by multivariate Cox, linear, and logistic regression. RESULTS Patients were of median (range) age 4.9 (0.2-15.4) years at diagnosis and followed up for 8.3 (0.04-26.8) years. Despite high 20-year overall survival (81.0%), progression-free and endocrine event-free survival (EEFS) were 47.2 and 20.8%, respectively. EEFS declined up to 15 years post-diagnosis, with hypothalamic involvement (P < .001) being implicated more than radiotherapy (P = .008) in earlier endocrinopathy; the reverse being true of its density (radiotherapy P < .001; hypothalamic involvement P = .006). GH deficiency (GHD) was most common (40.3%), followed by central precocious puberty (CPP, 26.0%), gonadotropin (GnD; 20.4%), TSH (13.3%), and ACTH (13.3%) deficiencies. GHD increased with later treatment eras (P < .01), but replacement did not increase progression. CPP was associated with future GnD (P < .05). Posterior pituitary dysfunction (PPD; 7.2%) occurred in 57.9% after only biopsies or shunt procedures, and was associated with 6/13 deaths; 50.2% became obese. Tumor extent, surgery, and increased endocrinopathy, rather than radiotherapy, predicted visuocognitive morbidity. CONCLUSIONS This first longitudinal OP/HSG-specific study demonstrates that hypothalamo-pituitary dysfunction evolves hierarchically over decades. Tumor location predicts its speed of onset and radiotherapy its density. GnD can evolve from previous CPP, whereas life-threatening PPD can occur after any surgery. Our data suggest that recent radiation-avoiding chemotherapeutic strategies have increased GHD without improving survival.

Real-time quantitative PCR analysis of pediatric ependymomas identifies novel candidate genes including TPR at 1q25 and CHIBBY at 22q12-q13

Loss of chromosome 22 and gain of 1q are the most frequent genomic aberrations in ependymomas, indicating that genes mapping to these regions are critical in their pathogenesis. Using real‐time quantitative PCR, we measured relative copy numbers of 10 genes mapping to 22q12.3‐q13.33 and 10 genes at 1q21‐32 in a series of 47 pediatric intracranial ependymomas. Loss of one or more of the genes on 22 was detected in 81% of cases, with RAC2 and C22ORF2 at 22q12‐q13.1 being deleted most frequently in 38% and 32% of ependymoma samples, respectively. Combined analysis of quantitative‐PCR with methylation‐specific PCR and bisulphite sequencing revealed a high rate (>60% ependymoma) of transcriptional inactivation of C22ORF2, indicating its potential importance in the development of pediatric ependymomas. Increase of relative copy numbers of at least one gene on 1q were detected in 61% of cases, with TPR at 1q25 displaying relative copy number gains in 38% of cases. Patient age was identified as a significant adverse prognostic factor, as a significantly shorter overall survival time (P = 0.0056) was observed in patients <2 years of age compared with patients who were >2 years of age. Loss of RAC2 at 22q13 or amplification of TPR at 1q25 was significantly associated with shorter overall survival in these younger patients (P = 0.0492 and P = < 0.0001, respectively). This study identifies candidate target genes within 1q and 22q that are potentially important in the pathogenesis of intracranial pediatric ependymomas.

A Two-Stage Model for In Vivo Assessment of Brain Tumor Perfusion and Abnormal Vascular Structure Using Arterial Spin Labeling

The ability to assess brain tumor perfusion and abnormalities in the vascular structure in vivo could provide significant benefits in terms of lesion diagnosis and assessment of treatment response. Arterial spin labeling (ASL) has emerged as an increasingly viable methodology for non-invasive assessment of perfusion. Although kinetic models have been developed to describe perfusion in healthy tissue, the dynamic behaviour of the ASL signal in the brain tumor environment has not been extensively studied. We show here that dynamic ASL data acquired in brain tumors displays an increased level of ‘biphasic’ behaviour, compared to that seen in healthy tissue. A new two-stage model is presented which more accurately describes this behaviour, and provides measurements of perfusion, pre-capillary blood volume fraction and transit time, and capillary bolus arrival time. These biomarkers offer a novel contrast in the tumor and surrounding tissue, and provide a means for measuring tumor perfusion and vascular structural abnormalities in a fully non-invasive manner.

Astrocytoma derived short-term cell cultures retain molecular signatures characteristic of the tumour in situ

The heterogeneity of tumours and uncertainties surrounding derived short-term cell cultures and established cell lines fundamentally challenge the research and understanding of tumour growth and development. When tumour cells are cultured, changes are inevitably induced due to the artificial growth conditions. Several recent studies have questioned how representative established cell lines or derived short-term cell cultures are of the tumour in situ. We have characterised gene expression changes induced by short-term culture in astrocytoma in order to determine whether derived short-term cell cultures are representative of the tumour in situ. In comparison to the majority of studies, paired biopsies and derived short-term cultures were investigated to reduce the effects of long-term culture and inter-tumour variability when comparing biopsies and derived cultures from tumours with the same histology from different individuals. We have used the Affymetrix GeneChip U133A to generate gene expression profiles of 6 paediatric pilocytic astrocytoma (PA) biopsies and derived short-term cell cultures and 3 adult glioblastoma multiforme (GBM) biopsies and derived short-term cultures. Significant differential gene expression is induced by short-term culture. However, when the biopsy and derived short-term cell culture samples were grouped according to tumour type (PA and GBM) a molecular signature of 608 genes showed significant differential expression between the groups. This gene cohort can distinguish PA and GBM tumours, regardless of the sample source, suggesting that astrocytoma derived short-term cultures do retain key aspects of the global tumour expression profile and are representative of the tumour in situ. Furthermore, these genes are involved in pathways and functions characteristic of adult GBM including VEGF signalling, hypoxia and TP53 signalling.

Molecular analysis of pediatric brain tumors identifies microRNAs in pilocytic astrocytomas that target the MAPK and NF-κB pathways

IntroductionPilocytic astrocytomas are slow-growing tumors that usually occur in the cerebellum or in the midline along the hypothalamic/optic pathways. The most common genetic alterations in pilocytic astrocytomas activate the ERK/MAPK signal transduction pathway, which is a major driver of proliferation but is also believed to induce senescence in these tumors. Here, we have conducted a detailed investigation of microRNA and gene expression, together with pathway analysis, to improve our understanding of the regulatory mechanisms in pilocytic astrocytomas.ResultsPilocytic astrocytomas were found to have distinctive microRNA and gene expression profiles compared to normal brain tissue and a selection of other pediatric brain tumors. Several microRNAs found to be up-regulated in pilocytic astrocytomas are predicted to target the ERK/MAPK and NF-κB signaling pathways as well as genes involved in senescence-associated inflammation and cell cycle control. Furthermore, IGFBP7 and CEBPB, which are transcriptional inducers of the senescence-associated secretory phenotype (SASP), were also up-regulated together with the markers of senescence and inflammation, CDKN1A (p21), CDKN2A (p16) and IL1B.ConclusionThese findings provide further evidence of a senescent phenotype in pilocytic astrocytomas. In addition, they suggest that the ERK/MAPK pathway, which is considered the major driver of these tumors, is regulated not only by genetic aberrations but also by microRNAs.

MRI abnormalities in children following sequential chemotherapy, hyperfractionated accelerated radiotherapy and high-dose thiotepa for high-risk primitive neuroectodermal tumours of the central nervous system.

Intensive postsurgical therapies have improved survival in children with primitive neuroectodermal tumour, but there is concern that the combination of chemotherapy and radiotherapy may result in a compound injury to normal brain. The purposes of this analysis were to characterise what types of imaging abnormalities occur, identify risk factors and explore how treatment‐related changes may be distinguished from tumour.

Is CSF cytology a useful diagnostic procedure in staging paediatric CNS tumours

Objectives:  To evaluate whether there are any factors that predict malignant cells being found in paediatric cerebrospinal fluid (CSF) samples. To determine whether CSF provides useful staging information not provided by magnetic resonance imaging (MRI) in paediatric patients with primary central nervous system (CNS) malignancy.