Prognostic implication of histopathological, immunohistochemical and clinical features of oligodendrogliomas: a study of 89 cases

HIP1R and vimentin immunohistochemistry predict 1p/19q status in IDH-mutant glioma

BACKGROUND

IDH-mutant gliomas are separate based on the codeletion of the chromosomal arms 1p and 19q into oligodendrogliomas IDH-mutant 1p/19q-codeleted and astrocytomas IDH-mutant. While nuclear loss of ATRX expression excludes 1p/19q codeletion, its limited sensitivity prohibits to conclude on 1p/19q status in tumors with retained nuclear ATRX expression.

METHODS

Employing mass spectrometry based proteomic analysis in a discovery series containing 35 fresh frozen and 72 formalin fixed and paraffin embedded tumors with established IDH and 1p/19q status, potential biomarkers were discovered. Subsequent validation immunohistochemistry was conducted on two independent series (together 77 oligodendrogliomas IDH-mutant 1p/19q-codeleted and 92 astrocytomas IDH-mutant).

RESULTS

We detected highly specific protein patterns distinguishing oligodendroglioma and astrocytoma. In these patterns, high HIP1R and low vimentin levels were observed in oligodendroglioma while low HIP1R and high vimentin levels occurred in astrocytoma. Immunohistochemistry for HIP1R and vimentin expression in 35 cases from the FFPE discovery series confirmed these findings. Blinded evaluation of the validation cohorts predicted the 1p/19q status with a positive and negative predictive value as well as an accuracy of 100% in the first cohort and with a positive predictive value of 83%; negative predictive value of 100% and an accuracy of 92% in the second cohort. Nuclear ATRX loss as marker for astrocytoma increased the sensitivity to 96% and the specificity to 100%.

CONCLUSIONS

We demonstrate that immunohistochemistry for HIP1R, vimentin, and ATRX predict 1p/19q status with 100% specificity and 95% sensitivity and therefore, constitutes a simple and inexpensive approach to the classification of IDH-mutant glioma.

Revisiting vimentin: a negative surrogate marker of molecularly defined oligodendroglioma in adult type diffuse glioma

Vimentin is a marker of epithelial-mesenchymal transformation and indicates poor prognosis in various cancers, but its role in diffuse gliomas remains unknown. We investigated the vimentin expression of diffuse gliomas according to the upcoming 2021 WHO classification, its variations due to mutational status, and its prognostic effects. We analyzed vimentin immunohistochemistry in 315 gliomas: a test set (n = 164) and a validation set (n = 151). RNA-seq and mutational information from The Cancer Genome Atlas (TCGA, n = 422) were also used for validation. Vimentin was diffusely positive in astrocytic tumors but negative in oligodendroglial tumors (ODGs) and its expression was significantly higher in isocitrate dehydrogenase (IDH) wild-type tumors. High vimentin expression was correlated with poor prognosis (hazard ratio [HR]: 5.99), but it was dependent on the new WHO grade which reflects both histologic features and genetics (HR: 1.28). Using the significant difference in vimentin expression between ODGs and astrocytic tumors, the positive and negative predictive values of the vimentin-based diagnosis for ODGs were 93.5% and 97.8% in the validation set. Along with additional alpha-thalassemia/mental retardation, X-linked (ATRX) immunohistostaining, the values were 98.3% and 97.8%, respectively. Vimentin is a useful ancillary marker for identifying ODGs when combined with routine histochemistry markers.

Nogo receptor-vimentin interaction: a novel mechanism for the invasive activity of glioblastoma multiforme

Nogo receptor (NgR) has been shown to inhibit the migration and invasion of human glioma cells. However, little is known regarding the regulatory mechanisms of NgR in glioblastoma multiforme (GBM). In this study, we propose a novel mechanism that regulates the maturation process of NgR through an interaction with vimentin. The inhibition of TGFβ1 activity by LY2109761 attenuated the migration/invasion of GBM cells by upregulating cell-surface NgR. Conversely, the treatment of GBM cells with TGFβ1 suppressed NgR maturation. We showed that NgR and vimentin interact, which could be a possible mechanism for the suppression of NgR maturation. The knockdown of vimentin suppressed the migration/invasion of GBM cells through the increased maturation of NgR. Finally, TCGA (The Cancer Genome Atlas) analysis also supported the association of NgR and vimentin. The maturation of NgR is regulated by the interaction of vimentin and NgR, which attenuates the invasive activity of GBM, and might be a potential therapeutic target for brain cancer.

A mechanism that prevents the maturation of a protective cell surface protein during the spread of brain cancer could be a therapeutic target. Aggressive glioblastoma multiforme tumors spread quickly, lowering survival chances. The transforming growth factor-beta 1 (TGFβ1) protein is implicated in the rapid spread of cancer cells through the brain’s white matter fibers. However, cancer spread can be limited by the mature form of a protein receptor called nogo receptor (NgR), which is expressed on white matter cell surfaces. Using human glioblastoma cell cultures, Seung-Hoon Lee and Myung-Shin Lee at Eulji University School of Medicine, Daejeon, South Korea, and co-workers demonstrated how the interaction between NgR and another protein enhances TGFβ1 pathway activity and prevents NgR maturing. When the team inhibited TGFβ1, the interaction was disrupted, allowing NgR maturation and preventing tumor spread.

The Cytoskeleton-A Complex Interacting Meshwork

The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.

Cerebellar Peduncle Localized Oligodendroglioma: Case Report and Review of the Literature

BACKGROUND

Oligodendrogliomas constitute 5% of all primary brain tumors and are the third most common cancer among intracranial tumors. More than 90% of oligodendrogliomas have supratentorial localization. Oligodendrogliomas arising in cerebellar peduncle are substantially rare, <1%. Up to now, 6 oligodendroglioma cases with cerebellar peduncle localization have been presented. We aimed to discuss our World Health Organization grade II oligodendroglioma case, which originated from cerebellar peduncle in the light of literature.

CASE DESCRIPTION

We report a case of 43-year-old woman. Her complaints were headache, perioral numbness and gait abnormality. Magnetic resonance imaging revealed cyst-like well-demarcated lesion localized in right cerebellar peduncle. Tumor excision was performed by turning around the tumor.

CONCLUSION

It should be kept in mind that oligodendrogliomas may be present as cerebellar peduncle localized tumors.

Predictors of clinical outcome in pediatric oligodendroglioma: meta-analysis of individual patient data and multiple imputation

OBJECTIVE Oligodendroglioma is a rare primary CNS neoplasm in the pediatric population, and only a limited number of studies in the literature have characterized this entity. Existing studies are limited by small sample sizes and discrepant interstudy findings in identified prognostic factors. In the present study, the authors aimed to increase the statistical power in evaluating for potential prognostic factors of pediatric oligodendrogliomas and sought to reconcile the discrepant findings present among existing studies by performing an individual-patient-data (IPD) meta-analysis and using multiple imputation to address data not directly available from existing studies. METHODS A systematic search was performed, and all studies found to be related to pediatric oligodendrogliomas and associated outcomes were screened for inclusion. Each study was searched for specific demographic and clinical characteristics of each patient and the duration of event-free survival (EFS) and overall survival (OS). Given that certain demographic and clinical information of each patient was not available within all studies, a multivariable imputation via chained equations model was used to impute missing data after the mechanism of missing data was determined. The primary end points of interest were hazard ratios for EFS and OS, as calculated by the Cox proportional-hazards model. Both univariate and multivariate analyses were performed. The multivariate model was adjusted for age, sex, tumor grade, mixed pathologies, extent of resection, chemotherapy, radiation therapy, tumor location, and initial presentation. A p value of less than 0.05 was considered statistically significant. RESULTS A systematic search identified 24 studies with both time-to-event and IPD characteristics available, and a total of 237 individual cases were available for analysis. A median of 19.4% of the values among clinical, demographic, and outcome variables in the compiled 237 cases were missing. Multivariate Cox regression analysis revealed subtotal resection (p = 0.007 [EFS] and 0.043 [OS]), initial presentation of headache (p = 0.006 [EFS] and 0.004 [OS]), mixed pathologies (p = 0.005 [EFS] and 0.049 [OS]), and location of the tumor in the parietal lobe (p = 0.044 [EFS] and 0.030 [OS]) to be significant predictors of tumor progression or recurrence and death. CONCLUSIONS The use of IPD meta-analysis provides a valuable means for increasing statistical power in investigations of disease entities with a very low incidence. Missing data are common in research, and multiple imputation is a flexible and valid approach for addressing this issue, when it is used conscientiously. Undergoing subtotal resection, having a parietal tumor, having tumors with mixed pathologies, and suffering headaches at the time of diagnosis portended a poorer prognosis in pediatric patients with oligodendroglioma.

Long-Term Outcome of Postoperative Irradiation in Patients with Newly Diagnosed WHO Grade III Anaplastic Gliomas

Purpose

Patients with anaplastic gliomas have a more favorable overall survival than patients with glioblastomas. In most analyses, WHO grade III and IV tumors are not analyzed separately. The present analysis reports outcome after postoperative radiotherapy in patients with WHO grade III gliomas.

Patients and methods

Between January 1988 and January 2007, 127 patients with WHO grade III tumors were treated with radiotherapy; the histological classification was pure astrocytoma in 104 patients, oligoastrocytoma in 12 and pure oligodendroglioma in 11 patients. Median age was 48 years. After the primary diagnosis, a biopsy had been performed in 72 patients; subtotal and total resections were performed in 37 and 18 patients, respectively. In all patients radiotherapy was applied with a median dose of 60 Gy in conventional fractionation. The median follow-up time was 18 months.

Results

Median overall survival was 17 months. Overall survival was significantly influenced by the extent of surgery. Median overall survival was 32 months after complete resection, 36 months after subtotal resection, and 12 months after biopsy. Median overall survival was 7 months for patients with anaplastic astrocytomas, 44 months for patients with mixed tumors, and 47 months for those with pure oligodendrogliomas. Age significantly influenced overall survival. Median progression-free survival was 9 months; the extent of neurosurgical resection significantly influenced progression-free survival.

Conclusion

Patients with WHO grade III anaplastic astrocytomas, oligodendrogliomas and oligoastrocytomas show favorable overall survival after postoperative radiotherapy compared with glioblastoma patients and should therefore be analyzed separately. Radiochemotherapy might further improve outcome.

Tumor cells with neuronal intermediate progenitor features define a subgroup of 1p/19q co-deleted anaplastic gliomas

The integrated diagnosis of anaplastic oligodendroglioma, IDH mutant and 1p/19q co-deleted, grade III (O3^id ) is a histomolecular entity that WHO 2016 classification distinguished from other diffuse gliomas by specific molecular alterations. In contrast, its cell portrait is less well known. The present study is focused on intertumor and intratumor, cell lineage-oriented, heterogeneity in O3^id . Based on pathological, transcriptomic and immunophenotypic studies, a novel subgroup of newly diagnosed O3^id overexpressing neuronal intermediate progenitor (NIP) genes was identified. This NIP overexpression pattern in O3^id is associated with: (i) morphological and immunohistochemical similarities with embryonic subventricular zone, (ii) proliferating tumor cell subpopulation with NIP features including expression of INSM1 and no expression of SOX9, (iii) mutations in critical genes involved in NIP biology and, (iv) increased tumor necrosis. Interestingly, NIP tumor cell subpopulation increases in O3^id recurrence compared with paired newly diagnosed tumors. Our results, validated in an independent cohort, emphasize intertumor and intratumor heterogeneity in O3^id and identified a tumor cell subpopulation exhibiting NIP characteristics that is potentially critical in oncogenesis of O3^id . A better understanding of spatial and temporal intratumor cell heterogeneity in O3^id will open new therapeutic avenues overcoming resistance to current antitumor treatments.

Analysis of expression and prognostic significance of vimentin and the response to temozolomide in glioma patients

Gliomas are the most common primary intracranial malignant tumors in adults. Surgical resection followed by optional radiotherapy and chemotherapy is the current standard therapy for glioma patients. Vimentin, a protein of intermediate filament family, could maintain the cellular integrity and participate in several cell signal pathways to modulate the motility and invasion of cancer cells. The purpose of the present research was to identify the relationship between vimentin expression and clinical characteristics and detect the prognostic and predictive ability of vimentin in patients with glioma. To determine the expression of vimentin in glioma tissues, paraffin-embedded blocks from glioma patients by surgical resection were obtained and evaluated by immunohistochemistry. To further investigate the association of vimentin expression with survival, we employed mRNA expression of vimentin genes from the Chinese Glioma Genome Atlas (CGGA) and the GSE 16011 dataset. Kaplan-Meier analysis and Cox regression model were used to statistical analysis. We detected positive vimentin straining in 84 % of high-grade compared to 47 % in low-grade glioma patients. Additionally, vimentin mRNA expression was correlated with glioma grade in both CGGA and GSE16011 dataset. Patients with low vimentin expression have longer survival than high expression. In multivariate analysis, vimentin was an independent significant prognostic factor for high-grade glioma patients. We also identified that glioblastoma patients with low vimentin expression had a better response to temozolomide therapy. Vimentin expression has a significant association with tumor grade and overall survival of high-grade glioma patients. Low vimentin expression may benefit from temozolomide therapy.

The role of neuropathology in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

TARGET POPULATION

Adult patients (age ≥18 years) who have suspected low-grade diffuse glioma.

QUESTION

What are the optimal neuropathological techniques to diagnose low-grade diffuse glioma in the adult?

RECOMMENDATION

LEVEL I: Histopathological analysis of a representative surgical sample of the lesion should be used to provide the diagnosis of low-grade diffuse glioma.

LEVEL III

Both frozen section and cytopathologic/smear evaluation should be used to aid the intra-operative assessment of low-grade diffuse glioma diagnosis. A resection specimen is preferred over a biopsy specimen, to minimize the potential for sampling error issues.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is testing for IDH1 mutation (R132H and/or others) warranted? If so, is there a preferred method?

RECOMMENDATION

LEVEL II

IDH gene mutation assessment, via IDH1 R132H antibody and/or IDH1/2 mutation hotspot sequencing, is highly-specific for low-grade diffuse glioma, and is recommended as an additional test for classification and prognosis.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is testing for 1p/19q loss warranted? If so, is there a preferred method?

RECOMMENDATION

LEVEL III

1p/19q loss-of-heterozygosity testing, by FISH, array-CGH or PCR, is recommended as an additional test in oligodendroglial cases for prognosis and potential treatment planning.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is MGMT promoter methylation testing warranted? If so, is there a preferred method?

RECOMMENDATION

There is insufficient evidence to recommend methyl-guanine methyl-transferase (MGMT) promoter methylation testing as a routine for low-grade diffuse gliomas. It is recommended that patients be enrolled in properly designed clinical trials to assess the value of this and related markers for this target population.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is Ki-67/MIB1 immunohistochemistry warranted? If so, is there a preferred method to quantitate results?

RECOMMENDATION

LEVEL III

Ki67/MIB1 immunohistochemistry is recommended as an option for prognostic assessment.

Ki-67 is a valuable prognostic factor in gliomas: evidence from a systematic review and meta-analysis

Ki-67 has been widely used as an indicator of cell proliferation in gliomas. However, the role of Ki-67 as a prognostic marker is still undefined. Thus, we conducted a meta-analysis of the published literatures in order to clarify the impact of Ki-67 on survival in glioma cases. Eligible studies were identified in PubMed, EMBASE, ISI Web of Science, Cochrane Central Register of Controlled Trials, Science Direct and Wiley Online Library with the last search updated on August 31, 2014. The clinical characteristics, overall survival (OS) and progression- free survival (PFS) together with Ki-67 expression at different time points were extracted. A total of 51 studies, covering 4,307 patients, were included in the current meta-analysis. The results showed that overexpression of Ki-67 can predict poor OS (HR=1.66, 95%CI: 1.53-1.80; Z=11.87; p=0.000) and poor PFS (HR=1.67, 95%CI: 1.47-1.91; Z=7.67; p=0.000) in gliomas. Moreover, subgroup analyses also indicated that high level of Ki-67 expression was related to poor OS and PFS in glioma patients regardless of region, pathology type, cut-off value and statistical method. In conclusion, the current meta-analysis revealed that Ki-67 expression might be a predicative factor for poor prognosis of glioma patients, emphasizing its importance as a predictor.

Incidence and survival of childhood central nervous system tumors: A report of the regional registry of childhood cancers in Auvergne-Limousin

INTRODUCTION

Central nervous system tumors (CNST) are the most lethal of solid tumors in childhood cancer.

PATIENTS AND METHODS

We report incidence and survival data for all CNST (International Classification of Diseases for Oncology third edition, category III or Xa) recorded in children under 15 years of age by the Auvergne-Limousin cancer registry for the period 1986-2009.

RESULTS

Annual incidence of all CNST was 3.27 per 100,000 and the male to female ratio was 0.95. Over 45.0% of CNST were glial. Astrocytomas (36.2%) showed the highest incidence for each age group except between 1 and 4 years where embryonal tumors were more common. For all CNST, no significant variation in incidence over time was observed for the evaluated period of 23 years (annual percent change: -0.4%, 95% CI, [-2.8-2.1]). Globally, 5 years overall survival was 67% [59-73] and had increased by more than 16% between 1986-1999 and 2000-2009, mainly due to better survival for astrocytomas, other gliomas, ependymomas and choroid plexus tumors (P=0.01).

CONCLUSION

We report that the incidence of CNST in Auvergne-Limousin is similar to that in the literature and did not increase between 1986 and 2009. In addition, 5 years overall survival increased after 1999, especially for surgically treatable tumors.

Roles and potential clinical applications of intermediate filament proteins in brain tumors

Intermediate filament (IF) proteins are cytoplasmic and nuclear cytoskeletal proteins. Of the ~70 IF proteins, nearly 12 are found in the nervous system, where their expression is largely cell-type specific. Astrocytes express glial fibrillary acidic protein (GFAP), whereas different neuron types contain neurofilament proteins, α-internexin, or peripherin. These proteins are often downregulated in brain cancer. In addition, brain cancer cells may also contain vimentin, nestin, and synemin, which are the IF proteins found in neural progenitor cells. In different brain tumor types, the expression of nestin, vimentin, and α-internexin appears to correlate with the clinical outcome. Experimental investigations have also demonstrated that IF proteins have distinct roles in specific brain tumor cell behaviors: nestin, for instance, is important for the proliferation of glioma cells, whereas synemin also affect their mobility. The mechanisms responsible for these effects involve the interaction of IF proteins with specific signaling pathways. Synemin, for instance, positively regulates glioma cell proliferation by antagonizing protein phosphatase 2A. Further evidence for the potential of IF proteins as therapeutic targets derives from animal models showing the influence of IF proteins on tumor growth. Nestin downregulation, for instance, dramatically reduced intracerebral glioma growth. Selective targeted therapies of IFs to date primarily include gene therapy approaches using nestin or GFAP gene promoters to drive transgene expression into glioma cells. Although attempts to identify small molecules specifically antagonizing IF proteins have been unsuccessful to date, it is anticipated that the identification of such compounds will be instrumental in expanding therapeutic approaches for brain tumors.

The impact of extent of resection on malignant transformation of pure oligodendrogliomas

Object

Recent evidence suggests that a greater extent of resection (EOR) extends malignant progression-free survival among patients with low-grade gliomas (LGGs). These studies, however, rely on the combined analysis of oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas—3 histological subtypes with distinct genetic and molecular compositions. To assess the value of EOR in a homogeneous LGG patient population and delineate its impact on LGG transformation, the authors examined its effect on newly diagnosed supratentorial oligodendrogliomas.

Methods

The authors identified 93 newly diagnosed adult patients with WHO Grade II oligodendrogliomas treated with microsurgical resection at Barrow Neurological Institute. Clinical, laboratory, and radiographic data were collected retrospectively, including 1p/19q codeletion status and volumetric analysis based on T2-weighted MRI.

Results

The median preoperative and postoperative tumor volumes and EOR were 29.0 cm3 (range 1.3–222.7 cm3), 5.2 cm3 (range 0–156.1 cm3), and 85% (range 6%–100%), respectively. Median follow-up was 75.4 months, and there were 14 deaths (15%). Progression and malignant progression were identified in 31 (33%) and 20 (22%) cases, respectively. A greater EOR was associated with longer overall survival (p = 0.005) and progression-free survival (p = 0.004); however, a greater EOR did not prolong the interval to malignant progression, even when controlling for 1p/19q codeletion.

Conclusions

A greater EOR is associated with an improved survival profile for patients with WHO Grade II oligodendrogliomas. However, for this particular LGG patient population, the interval to tumor transformation is not influenced by cytoreduction. These data raise the possibility that the capacity for microsurgical resection to modulate malignant progression is mediated through biological mechanisms specific to nonoligodendroglioma LGG histologies.

Cerebellopontine angle oligodendroglioma in a child: first case report

The reported incidence of oligodendrogliomas in the paediatric population is less than 1 %. The posterior fossa is a rare location, with the vast majority arising in the cerebral hemispheres. We report the first paediatric case of a WHO grade II oligodendroglioma arising in the cerebellopontine angle (CPA). CPA oligodendrogliomas in children appear to behave aggressively and adjuvant therapy must be considered early; especially when complete resection cannot be achieved.

Oligodendroglioma (WHO grade I) in a young epilepsy patient: a specific entity lying within the spectrum of dysembryoplastic neuroepithelial tumor?

We studied a frontal lobe subcortical cystic tumor that had been resected from a 13-year-old girl with a 3-year history of intractable partial seizure. Currently, more than 13 years after surgery, the patient remains recurrence-free and has no neurological deficits. Histological examination showed that the tumor was non-infiltrating and paucicellular with a mucinous matrix, and consisted of fairly uniform small cells with round to oval nuclei. Within the mucinous matrix, the tumor cells were often arranged in pseudorosettes around small blood vessels. Mitotic activity and necrosis were absent, with a Ki-67 labeling index of <1%. Based on the immunohistochemical and ultrastructural findings, the constituent tumor cells were considered to be those of oligodendroglioma, including mini-gemistocytes and gliofibrillary oligodendrocytes. No neuronal elements were identified. Features of cortical dysplasia (FCD Type 1) were evident in the cortex covering the lesion. The surrounding white matter also contained a significant number of ectopic neurons. The entire pathological picture appeared to differ somewhat from that of ordinary oligodendroglioma (WHO grade II). Considering the clinical and pathological features, the present unusual oligodendroglioma appeared to represent a previously undescribed form of oligodendroglioma (WHO grade I) lying within the spectrum of dysembryoplastic neuroepithelial tumor (DNT; WHO grade I). Simultaneously, the present oligodendroglioma also raises the question of whether or not oligodendrocyte-like cells of DNTs truly show neurocytic differentiation.

Prognostic significance of neuronal marker expression in glioblastomas

PURPOSE

Glioblastomas are the most malignant tumors of central nervous system neoplasms and are well known for their biological heterogeneity. Contrary to the putative hypothesis of purely glial differentiation in glioblastomas, they often demonstrate immunopositivity for neuronal markers. However, the significance of their neuronal marker expression is still controversial. To evaluate the prognostic implication of neuronal expression in glioblastoma, this study investigated the expression of neuronal markers in a large series of glioblastoma patients in terms of patient survival rate.

METHODS

Expression of synaptophysin, neurofilament protein, and NeuN was explored using immunohistochemistry in 88 cases of glioblastoma. Clinicopathological variables as well as patients' survival data were compared according to the immunopositivity of cases.

RESULTS

Sixty-one of the 88 tumors (69.3 %) were positive for at least one neuronal marker. Synaptophysin positivity was observed in 43 cases (48.9 %). Neurofilament protein and NeuN were positive in 38 (43.2 %) and 42 cases (47.7 %), respectively. There was no statistically significant difference in overall survival and progression-free survival in association with neuronal marker expression. However, gross total removal or combined radiotherapy and chemotherapy significantly prolonged survival (P=0.041 and 0.044). Cox's proportional hazard model revealed that NeuN expression was the independent prognostic factors in progression-free survival (P=0.012).

CONCLUSIONS

Although the correlation of neuronal marker expression and clinical outcome in glioblastoma is of considerable interest, the presented data support the limited prognostic value of neuronal marker expression in glioblastoma.

Imaging characteristics of oligodendrogliomas that predict grade

BACKGROUND AND PURPOSE

Oligodendrogliomas are tumors that have variable WHO grades depending on anaplasia and astrocytic components and their treatment may differ accordingly. Our aim was to retrospectively evaluate imaging features of oligodendrogliomas that predict tumor grade.

MATERIALS AND METHODS

The imaging studies of 75 patients with oligodendrogliomas were retrospectively reviewed and compared with the histologic grade. The presence and degree of enhancement and calcification were evaluated subjectively. rCBV and ADC maps were measured. Logistic linear regression models were used to determine the relationship between imaging factors and tumor grade.

RESULTS

Thirty of 75 (40%) tumors enhanced, including 9 of 46 (19.6%) grade II and 21 of 29 (72.4%) grade III tumors (P < .001). Grade III tumors showed lower ADC values compared with grade II tumors (odds ratio of a tumor being grade III rather than grade II = 0.07; 95% CI, 0.02-0.25; P = .001). An optimal ADC cutoff of 925 10(-6) mm(2)/s was established, which yielded a specificity of 89.1%, sensitivity of 62.1%, and accuracy of 78.7%. There was no statistically significant association between tumor grade and the presence of calcification and perfusion values. Multivariable prediction rules were applied for ADC < 925 10(-6) mm(2)/s, the presence of enhancement, and the presence of calcification. If either ADC < 925 10(-6) mm(2)/s or enhancement was present, it yielded 93.1% sensitivity, 73.9% specificity, and 81.3% accuracy. The most accurate (82.2%) predictive rule was seen when either ADC < 925 10(-6) mm(2)/s or enhancement and calcification were present.

CONCLUSIONS

Models based on contrast enhancement, calcification, and ADC values can assist in predicting the grade of oligodendrogliomas and help direct biopsy sites, raise suspicion of sampling error, and predict prognosis.

Hypoxia-inducible factor-1-regulated protein expression and oligodendroglioma patient outcome: comparison with established biomarkers and preoperative UCSF low-grade scoring system

Methods for predicting outcome for patients with oligodendrogliomas and anaplastic oligodendrogliomas (AOs) are limited. Hypoxia-inducible factor-1α (HIF-1α) controls many proteins involved in glycolysis and angiogenesis including VEGF, Glut-1, and CA-IX. We examined whether expression of HIF-1α and other hypoxia-regulated molecules (HRM) can predict overall (OS) and progression-free (PFS) survival. We correlated these data with more established biomarkers and a published preoperative scoring system. We prospectively collected tissue samples and followed outcomes of 50 patients with oligodendrogliomas and 32 with AOs. Tumor tissues were stained for measures of proliferative index, microvascular density, IDH-1 mutational status, and HRMs. We retrospectively analyzed preoperative imaging and clinical data based on the UCSF Scoring System (good prognostic indicators: Karnofsky Performance Scale (KPS) score > 80, age < 50 years, tumor diameter < 4 cm, noneloquent tumor location) and correlated these with immunohistochemical markers, 1p19q chromosomal status, and compared both with patient PFS and OS. Mean follow-up was 85.6 ± 41.4 months. HRMs showed higher expression in AOs than in oligodendrogliomas. Both 1p19q codeletion and IDH-1 mutation predict outcome of patients with both oligodendroglioma and AO. The UCSF score is a strong predictor for oligodendrogliomas patient outcome and is strengthened by IDH-1 and 1p19q status. Glut-1 may be useful in predicting PFS in AOs. Proliferation index >5 for oligodendrogliomas and KPS ≤ 80 for AOs predict a worse prognosis. Immunohistochemical markers of HRMs show a significantly higher expression in anaplastic variants of oligodendrogliomas and may contribute to the prediction of survival in these patients.

Molecular prognostic factors of anaplastic oligodendroglial tumors and its relationship: a single institutional review of 77 patients from China

The increased chemosensitivity of oligodendroglial tumors has been associated with loss of heterozygosity (LOH) on chromosomes 1p and 19q. Other clinical and molecular factors have also been identified as being prognostic and predictive for treatment outcome. Seventy-seven patients with anaplastic oligodendroglioma (AO) or anaplastic oligoastrocytoma (AOA), treated in Beijing Tiantan Hospital from 2006 through 2008, were reviewed. LOH 1p, LOH 19q, IDH1 mutation, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and protein expression level of MGMT, P53, EGFR, and Ki-67 were evaluated. Age at diagnosis, LOH 1p and 19q, IDH1 mutation, P53 expression level, reoperation when progression, and adjuvant chemotherapy were statistically significant factors for overall survival (OS) in univariate analysis. Further multivariate analysis showed that age at diagnosis (P = .010), LOH 1p and 19q (P = .016), IDH1 mutation (P = .011), and reoperation after progression (P = .048) were independent predictors for longer survival in these patients. Nonrandom associations were found between LOH 1p and LOH 19q, MGMT promoter methylation and LOH 1p or 19q, IDH1 mutation and LOH 1p and 19q, IDH1 mutation and MGMT promoter methylation, whereas mutual exclusion was found between MGMT promoter methylation and MGMT expression level. The present study confirmed that age at diagnosis, LOH 1p and 19q, IDH1 mutation, and reoperation after progression were independent significant prognostic factors for patients with anaplastic oligodendroglial tumors. Inter-relationship between LOH 1p, LOH 19q, IDH1 mutation, MGMT promoter methylation, and MGMT expression level were also revealed. Future clinical trials for AO and AOA should consider the molecular alterations of patients.

Molecular genetics, imaging and treatment of oligodendroglial tumours

The discovery of a genetic signature of chemosensitivity and prognosis in oligodendroglial tumours prompted a new optimism in glioma management. After more than a decade since the initial reports, where do we stand in the current management of oligodendroglial tumours? This review focuses on the latest molecular genetics, imaging characteristics, and recent trials of treatment paradigms for these tumours.

PepT2 transporter protein expression in human neoplastic glial cells and mediation of fluorescently tagged dipeptide derivative β-Ala-Lys-Nε-7-amino-4-methyl-coumarin-3-acetic acid accumulation

Object

The present study was aimed at analyzing the accumulation of the fluorescently tagged dipeptide derivative, β-Ala-Lys-Nε-7-amino-4-methyl coumarin-3-acetic acid (AMCA), in primary cultures of human neoplastic glial cells. This molecule is a highly specific reporter used to investigate the dipeptide transport system hPepT2.

Methods

In this study the authors used immunocytochemical methods to determine the cell-specific accumulation of a small and fluorescently tagged reporter molecule named β-Ala-Lys-Nε-AMCA to detect dipeptide transport capacity of neoplastic glial cells. Furthermore, specific mRNA levels were quantified using Northern blot analysis and the tissue distribution of hPepT2 mRNA transcripts was demonstrated with in-situ hybridization histochemical analysis.

Results

Recent fluorescent immunocytochemical analyses have revealed that β-Ala-Lys-Nε-AMCA specifically accumulates within anaplastic cells of astrocytic lineage but not in anaplastic oligodendrocytes or neurons. Northern blot analysis demonstrated that human hPepT2 mRNA is specifically detected in primary cell cultures of human glioblastoma but not in oligodendroglioma. Moreover, in situ hybridization analyses revealed an astrocytic localization of hPepT2 transcripts in human glioblastoma and astrocytoma cells. The hPepT2 transcription levels were clearly dependent on the grade of glial cell differentiation: within low-grade gliomas (WHO Grade II), more hPepT2 mRNA was detected compared with tumors of a higher grade of dedifferentiation (WHO Grade IV). Analysis of expression levels of hPepT2 mRNA in human neoplastic glial cells xenografted into the brains of athymic rats (han rnu+/+) showed a markedly increased expression of hPepT2 after 2 weeks of growth in vivo compared with the primary counterparts grown in vitro.

Conclusions

The authors concluded that expression of the hPepT2 transporter protein is a characteristic of glial cells of astrocytic lineage, and is dependent on the grade of astroglial cell differentiation and the extracellular matrix (here brain neuropil). The authors found that β-Ala-Lys-Nε-AMCA is as an excellent reporter molecule for assessing neoplastic glial cell function and physiological characteristics.

Differential proteome analysis of human gliomas stratified for loss of heterozygosity on chromosomal arms 1p and 19q

Combined deletion of chromosomal arms 1p and 19q is an independent prognostic marker in patients with oligodendroglial brain tumors, including oligodendrogliomas and oligoastrocytomas. However, the relevant genes in these chromosome arms and the molecular mechanisms underlying the prognostic significance of 1p/19q deletion are yet unknown. We used two-dimensional difference gel electrophoresis followed by mass spectrometry to perform a proteome-wide profiling of low-grade oligoastrocytomas stratified for the presence or absence of 1p/19q deletions. Thereby, we identified 22 different proteins showing differential expression in tumors with or without combined deletions of 1p and 19q. Four of the differentially expressed proteins, which are vimentin, villin 2 (ezrin), annexin A1, and glial fibrillary acidic protein, were selected for further analysis. Lower relative expression levels of these proteins in 1p/19q-deleted gliomas were confirmed at the protein level by Western blot analysis and immunohistochemistry. Furthermore, sequencing of sodium bisulfite-treated tumor DNA revealed more frequent methylation of 5'-CpG islands associated with the VIM and VIL2 genes in 1p/19q-deleted gliomas when compared with gliomas without these deletions. In summary, we confirm proteome-wide profiling as a powerful means to identify candidate biomarkers in gliomas. In addition, our data support the hypothesis that 1p/19q-deleted gliomas frequently show epigenetic down-regulation of multiple genes due to aberrant methylation of the 5'-CpG islands.

Osteopontin regulates human glioma cell invasiveness and tumor growth in mice

Human malignant glioma cells are characterized by local invasion. In the present study, we investigated the role of osteopontin (OPN) in the invasiveness of human glioma cells isolated from grade IV tumors. We found that the expression levels of OPN in these cell lines paralleled matrix metalloproteinase-2 (MMP-2) expression and cell invasiveness potential. When U87MG glioma cells (with a high-OPN expression level) were stably transformed with specific small hairpin RNA to knock down OPN expression, MMP-2 secretion, cell invasiveness, and tumor growth in implanted brains were dramatically reduced. Conversely, forced expression of OPN in GBM-SKH glioma cells (which expressed OPN at a low level) increased MMP-2 secretion, enhanced cell invasiveness, and increased tumor growth in a rodent xenograft model. Expression of OPN was associated with increased expression of vimentin and decreased expression of glial fibrillary acidic protein. Treatment of glioma cells with 5-aza-2′-deoxycytidine (5-aza-dC) suppressed OPN expression in a concentration-dependent manner. Suppression of OPN expression by 5-aza-dC was associated with reductions in MMP-2 secretion, vimentin expression, cell invasion, intravasation, and tumor growth. These data suggest that OPN may play important roles in regulating cell invasion in glioma cells and that 5-aza-dC may serve as a therapeutic agent for human gliomas.

Platelet-derived growth factor expression correlates with tumor grade and proliferative activity in human oligodendrogliomas

BACKGROUND

For the last one and a half decade, it has been found that platelet-derived growth factor (PDGF) promotes glial tumor growth through autocrine and paracrine loops, by expression of PDGFalpha receptor (PDGFRalpha) on glioma cells and PDGFbeta receptor (PDGFRbeta) on proliferating endothelial cells. However, studies on oligodendrogliomas, correlating expression of PDGF and its receptor with tumor grade and proliferative activity, through MIB-1 labeling index (LI) are relatively few as compared to astroglial counterpart.

METHODS

Formalin-fixed paraffin-embedded tissues from 55 cases of oligodendrogliomas (34 World Health Organization [WHO] grade II and 21 WHO grade III tumors) were subjected to immunohistochemistry. MIB-1 LI was calculated, and a semiquantitative scoring system for expression of PDGF and PDGFRalpha was used.

RESULTS

MIB-1 LI and PDGF expression increased with histologic grades of malignancy ("t" test, P < .001 and Mann Whitney test, U = 109, P < .001 respectively). The PDGF expression scores had a positive correlation with MIB-1 LI, irrespective of tumor grade (Pearson's correlation coefficient, r = 0.566; P < .001). However, there was no significant difference of PDGFRalpha expression between 2 grades of tumors.

CONCLUSIONS

The results of this study showed that MIB-1 LI is a rapid and cost-effective modality for predicting tumor grade in oligodendrogliomas. Immunohistochemistry for PDGF was found to be useful in differentiating various grades of oligodendroglioma, and therefore, it may be involved in tumor cell proliferation and malignant transformation. Platelet-derived growth factor receptor alpha, although expressed in oligodendroglial neoplasms, was not found to be useful in predicting tumor grade.

Does radiosurgery have a role in the management of oligodendrogliomas?

Object

In this study the authors evaluated the role of stereotactic radiosurgery (SRS) in the management of progressive or newly diagnosed small-volume oligodendrogliomas. Tumor control, survival, and complications were assessed in patients with oligodendroglioma who underwent Gamma Knife radiosurgery as a primary or adjuvant procedure.

Methods

The authors retrospectively reviewed 30 patients with oligodendroglioma (12 Grade II and 18 Grade III) who underwent SRS between 1992 and June 2006 at the University of Pittsburgh. The median patient age was 43.2 years (range 10.8–75.4 years). Twenty-four patients had previously undergone resection of the tumor, whereas tumors in 6 were diagnosed based on biopsy findings. The SRS was performed in 25 patients who had imaging-defined tumor progression despite prior fractionated radiation (22 patients) and/or chemotherapy (20 patients). The median target volume was 15.4 cm3 (range 0.07–48.7 cm3) and the median margin dose was 14.5 Gy (range 11–20 Gy).

Results

At an average of 39.2 months of follow-up (range 12–133 months), 17 patients were dead and 13 were living. The overall survival rates from diagnosis to 5 and 10 years were 90.9 and 68.2%, respectively, for Grade II and 52.1% at 5 years and 26.1% at 10 years for Grade III. Factors associated with an improved progression-free survival included lower tumor grade and smaller tumor volume. In 13 patients who had loss of heterozygosity testing, patients with 1p19q loss of heterozygosity had a significantly improved survival after diagnosis (p = 0.04).

Conclusions

The SRS modality is a minimally invasive additional option for patients with residual or recurrent oligodendrogliomas. It may also be considered as an alternative to initial resection in small-volume tumors located in the cortical brain region.

Molecular pathology of oligodendroglial tumors

The term oligodendroglioma was created by Bailey, Cushing, and Bucy based on the observation that these tumors share morphological similarities with oligodendrocytes (Bailey and Cushing 1926; Bailey and Bucy 1929). However, a convincing link between oligodendrocytes and oligodendrogliomas still needs to be shown. Oligoastrocytomas or mixed gliomas are histologically defined by the presence of oligodendroglial and astrocytic components. According to the WHO classification of brain tumors, oligodendroglial tumors are separated into oligodendrogliomas WHO grade II (OII), anaplastic oligodendrogliomas WHO grade III (OIII), oligoastrocytomas WHO grade II (OAII), anaplastic oligoastrocytomas WHO grade III (OAIII), and glioblastomas with oligodendroglioma component WHO grade IV (GBMo) (Louis et al. 2007).The perception of oligodendroglial tumors has changed in recent years. The diagnosis of oligodendroglioma or oligoastrocytomas is made much more frequently than 10 years ago. Treatment modalities have been advanced and novel concepts regarding the origin of oligodendroglial tumors have been developed. This review focuses on recent developments with impact on the diagnosis and understanding of molecular mechanisms in oligodendroglial tumors.

Predictive factors for overall and progression-free survival, and dissemination in oligodendroglial tumors

The pattern of recurrence and predictive factors for tumor progression, dissemination and survival in oligodendroglial tumors were investigated. 56 consecutive patients with oligodendroglial tumors were retrospectively analyzed to determine the predictive significance of various factors, including World Health Organization grade, loss of chromosomes 1p and 19q, and immunohistochemical features of TP53, O(6)-methylguanine-deoxyribonucleic-acid-methyltransferase, CD44H, nestin, and Ki-67. Eleven patients developed dissemination, and had significantly shorter post-progression survival compared to ten patients with local recurrence. Univariate analysis showed that retention of chromosome 1p or 19q, Ki-67 labeling index > or = 25%, diffuse expression of nestin, and p53 labeling index > or = 10% were unfavorable factors for overall, progression-free, and dissemination-free survival. Multivariate analysis showed that Ki-67 labeling index > or = 25% and diffuse expression of nestin were significant for dissemination-free survival. In conclusion, post-progression survival shows significant differences between patients with local and disseminated recurrence. Ki-67 labeling index and nestin expression pattern are useful markers to predict dissemination.

Incidence of and survival from oligodendroglioma in Denmark, 1943-2002

We established the nationwide, population-based incidence of oligodendroglioma in Denmark during 59 years of monitoring and compared the overall survival of patients with oligodendroglial tumors during the periods 1943-1977 and 1978-2002. On the basis of reports in the Danish Cancer Registry, 1,304 cases of oligodendroglioma were included in the study. We calculated sex- and age-specific incidence rates in 5-year age intervals and for 5-year calendar periods. Overall survival was estimated by the Kaplan-Meier method. In the period 1943-2002, the incidence rate of oligodendroglioma was less than 1 case per 100,000 person-years, but varied somewhat when viewed across isolated periods. Comparison of the incidence rate before and after the introduction of CT scanning did not reveal a significant difference in the incidence rate. The median survival increased from 1.4 years (95% confidence interval [CI], 1.0-1.6) to 3.4 years (95% CI, 2.6-4.2) during the period of study. The overall incidence of oligodendroglioma showed a relatively stable pattern over nearly 60 years of monitoring. Overall survival improved significantly during the study period, which could partly be due to improved diagnostic methods and treatment options.

Chromosome 1p and 19q deletions in malignant glioneuronal tumors with oligodendroglioma-like component

Malignant glioneuronal tumors (MGNT) are suggested to be a new entity of glioma defined morphologically as any malignant glioma showing immunohistoichemical evidence of neuronal differentiation. We encountered seven cases of MGNT with oligodendroglioma-like component and investigated alternations of chromosome 1p and 19q in these tumors. Seven patients ranged from 33 to 62 years of age, four females and three males. Immunohistochemical study of these tumors was performed using neuronal markers (synaptophysin, neurofilament, beta-tubulin, chromogranin A and NeuN), astrocytic marker (GFAP) and Ki-67. We undertook a molecular cytogenetic study of tumor specimens obtained from seven patients using fluorescence in situ hybridization (FISH) with DNA probes mapping to chromosome 1p36, 1q25, 19p13 and 19q13. Histologically, these tumors resembled anaplastic oligodendroglioma. Immunohistochemically, tumor cells were immunoreactive for synaptophysin (7/7), neurofilament (6/7), beta-tubulin (5/7), chromogranin A (4/7), NeuN (2/7) and GFAP (7/7). The Ki-67 labeling index ranged from 4.5% to 20.7%. FISH analysis demonstrated either 1p or 19q deletion in all seven cases (100%) and both 1p and 19q deletions in five cases (71%). The 1p deletion was detected in six of seven cases (86%) and 19q deletion was also detected in six (86%). 1p and 19q deletions were present in MGNT, especially those with oligodendroglial components. We suggest that the oligodendroglial-like feature was associated with not only 1p or 19q loss but also differentiation along neuronal cell lines as a factor of favorable prognosis in glial tumors. It is inappropriate to make a diagnosis of oligodendroglioma based only on morphological resemblance to oligodendroglia.

The Differential Diagnosis of Central Nervous System Tumors: A Critical Examination of Some Recent Immunohistochemical Applications

Context.—As we write, novel antibodies that may well alter the routine practice of surgical neuropathology are in development, characterization, and the early stages of clinical use. These will be used for purposes of tumor subclassification, as prognostic markers, as identifiers of potential therapeutic targets, and as predictors of treatment response.

Objective.—To provide for nonspecialists a critical assessment of the peer-reviewed literature (necessarily colored by our own experience) as it pertains to several immunohistochemical reagents that have been recently forwarded as adjuncts to the histologic typing of central nervous system tumors.

Data Sources.—We address in these pages only antibodies that are commercially available, that have been the subjects of multiple published series, and that we have had occasion to use in the course of everyday problem solving.

Conclusions.—Discussion concentrates on the use of 4 antibodies: BAF47 in the diagnosis of atypical teratoid/ rhabdoid tumor, OCT4 in intracranial germinoma, β-catenin in craniopharyngioma, and NeuN as a marker of neuronal differentiation in neuroepithelial neoplasms.

Molecular pathogenesis of adult brain tumors and the role of stem cells

Primary brain tumors consist of neoplasms with varied molecular defects, morphologic phenotypes, and clinical outcomes. The genetic and signaling abnormalities involved in tumor initiation and progression of the most prevalent adult primary brain tumors, including gliomas, meningiomas, and medulloblastomas, are described in this article. The current understanding of the cell-of-origin of these neoplasms is reviewed, which suggests that the malignant phenotype is propelled by cells with stem-like qualities. A comprehensive understanding of the molecular basis of transformation and the cell-of-origin of these neoplasms will enable the formulation of more targeted treatment alternatives that could improve survival and quality of life.

Up-regulation of vimentin expression in low-density malignant glioma cells as immediate and late effects under irradiation and temozolomide treatment

Nervous system tumors are one of the leading causes of cancer related death. Specific mechanisms facilitating the invasive behavior of gliomas remain obscure. Advanced simulation models of the in vivo response to therapy conditions should potentially improve malignant glioma treatment. Expressional profiling of vimentin--one of reliable pro-invasive tumor makers--in those simulation models was the goal of this study, in order to estimate a pro-invasive response of surviving malignant glioma cells under clinically relevant therapeutic conditions. Human U87-MG malignant glioma cells were used. These cells are characterized by the wild p53-phenotype, which is relevant for the majority of primary malignant glioblastomas. Experimental design foresaw the cells to undergo either irradiation or chemo-treatment with temozolomide alone, or combined treatment. Expression profiling of vimentin was performed by quantitative "Real-Time"-PCR under all treatment conditions simulating diverse tumor regions. Here we demonstrated that vimentin expression patterns in human malignant glioma cells strongly depend on cellular density, algorithms of drug delivery and chemo/radio treatment. Substantial differences were recognized between immediate and late therapy effects. Significant increase in vimentin expression levels was detected particularly in low-density cell cultures under durable treatment with constant concentration levels of temezolomide. Simulation of variable intratumoral regional conditions (central intratumoral regions vs. disseminated malignant cells in peripheral regions) demonstrated differential response of vimentin expression in malignant glioma cell cultures treated under clinically relevant conditions. Slight ebbing of expression levels as late effects of the treatment in confluent cultures may correspond to necrotic processes clinically observed in central intratumoral regions. Contrary, in disseminated malignant cells of peripheral regions therapy resulted in vimentin-inducing effects. This is in agreement with the clinical observations of an increased aggressiveness and malignancy grade of post-operatively chemo/radio-treated malignant gliomas.

Neuronal features of oligodendrogliomas--an ultrastructural and immunohistochemical study

AIMS

To assess neuronal differentiation in oligodendrogliomas (ODGs).

METHODS AND RESULTS

An electron microscopic and immunohistochemical study of 41 consecutive cases was performed. In all cases, tumour cells with neuritic structures were identified ultrastructurally, including synapses and neurosecretory granules. For the immunohistochemical identification of synaptophysin, monoclonal antibody clones 27G12, Snp88 and SY38 and a polyclonal antibody were compared in optimized protocols on slides from a spectrum of tissues and 16 ODGs. 27G12 gave the best signal-to-noise ratio, while SY38 gave the poorest. When 27G12 was applied on all 41 ODGs, widespread immunoreactivity was obtained in 100%. Among three antibodies to chromogranin compared similarly, clone LK2H10 and a polyclonal antibody gave identical patterns of immunoreactivity, whereas clone DAK-A3 gave weaker reactions. When LK2H10 was applied on all tumours, staining was found in 12 (29%). All tumours but one stained strongly for glial fibrillary acidic protein and all for synapsin I. Fluorescence in situ hybridization analysis showed a concomitant 1p/19q deletion in 12/16 ODGs.

CONCLUSIONS

Our study provides evidence for widespread neuronal differentiation in ODGs, suggesting that these tumours may be derived from progenitor cells with limited commitment. Antibody selection and protocol optimization are mandatory for reliable immunohistochemistry results.

Proposal of a scoring scale as a survival predictor in intracranial oligodendrogliomas

INTRODUCTION

Histological, clinical and radiological features, and molecular genetic analysis are among the factors that have been considered in defining the prognosis of oligodendrogliomas (OD), but they have yielded conflicting results. The purpose of this study was to test out a scoring scale based on clinical, radiological, pathological and molecular features.

MATERIAL AND METHOD

To identify factors with prognostic significance, we analyzed 87 treated patients with a histological diagnosis of OD. Of the parameters analyzed, age, onset, clinical status, radiological enhancement, histological necrosis, mitosis and chromosomal anomalies emerged as significant prognosis factors using univariate analysis. Multivariate analysis revealed age and chromosomal anomalies as independent factors of survival.

RESULTS

The factors with a significant prognostic value were combined to determine which grouping factors best predict outcome. The proposed score is a pure number resulting from a combination of: 2 major factors: age and chromosomal anomalies (scored 3-0); 5 minor factors: onset, clinical examination, necrosis, mitoses (scored 1-0), and radiological enhancement (scored 2-0). According to our scale, 10 survival curves were produced for overall survival. Recursive partitioning of patients with the nearest score and outcome produced four groups with a significant difference in survival (p=10(-5)). The power of both the scale and the partitioned groups for predicting outcome was more accurate than the WHO and St Anne grading systems, and the molecular sub-classification.

CONCLUSIONS

Our scale is a plausible way of classifying patients harboring intracranial OD according to expected survival.

Comparative analysis of NeuN immunoreactivity in primary brain tumours: conclusions for rational use in diagnostic histopathology

AIMS

NeuN is considered to be a marker of neuronal differentiation in brain tumours. Our aim was to perform, for the first time, a systematic and comparative analysis of NeuN expression in all major brain tumour subtypes to provide guidance for the rational use of NeuN immunohistochemistry in diagnostic histopathology.

METHODS AND RESULTS

Anti-NeuN immunohistochemistry was performed on paraffin-embedded biopsy specimens of 106 diffuse astrocytomas, 100 pilocytic astrocytomas, 107 ependymomas, 59 1p-aberrant oligodendroglial neoplasms, 115 glioblastomas, 115 medulloblastomas, 14 gangliogliomas/gangliocytomas and 10 central neurocytomas. We found no NeuN expression in pilocytic astrocytoma, whereas all other investigated tumour subtypes showed focal or widespread expression in varying proportions of cases. Comparing NeuN expression in clear cell tumours, widespread NeuN expression had a positive predictive value of 76.9% (95% confidence interval 46.2, 95.0) for central neurocytoma. Lack of NeuN expression had a positive predictive value of 87.3% (76.5, 94.4) for oligodendroglioma.

CONCLUSIONS

Immunohistochemistry can detect NeuN expression in all major brain tumour subtypes except pilocytic astrocytoma. In the individual case, assessment of NeuN expression may be helpful in the differential diagnosis of clear cell primary brain tumours but does not seem to be useful for the differential diagnosis of other brain tumour subtypes.

Is current therapy of malignant gliomas beneficial for patients? Proteomics evidence of shifts in glioma cells expression patterns under clinically relevant treatment conditions

The most common human brain tumours - gliomas - have poor prognosis with and without treatment. The current therapy conditions act sub-lethally and cannot effectively suppress the proliferation of glioma cells. Here we show differential protein expression patterns in surviving human malignant U87-MG glioma cells under clinically relevant chemo/radiotherapy. In parallel experiments, the cells underwent either irradiation (2 Gy, 200 KV X-ray) or chemotreatment with 30 microg/mL of temozolomide in the cultivation medium or combined chemo/radiation treatment. The cell cultures were treated during 5 days from day 4 until day 9 of growth. Modulated expression patterns of vimentin and RhoA GTPase indicate a potentially increasing grade of malignancy in treated cell fractions correlating well with extremely aggressive tumour phenotypes observed clinically at recidivation of treated malignant gliomas.

From the archives of the AFIP: Oligodendroglioma and its variants: radiologic-pathologic correlation

Oligodendroglioma is the third most common glial neoplasm and most commonly arises in the frontal lobe. It occurs in males more frequently, and the peak manifestation is during the 5th and 6th decades. Children are affected much less commonly. The clinical presentation is often of several years duration with most patients presenting with seizures, reflecting the strong predilection of this tumor to involve the cortical gray matter. Current histopathologic classification schemes recognize two main types of tumors: well-differentiated oligodendroglioma and its anaplastic variant. Less commonly, neoplastic mixtures of both oligodendroglial and astrocytic components occur and are termed oligoastrocytomas, with both well-differentiated and anaplastic forms. Surgical resection is the mainstay of initial treatment, and many patients experience a long progression-free period. Recent genotyping has revealed chromosomal loss of 1p and 19q as a genetic signature in most oligodendrogliomas, and these tumors respond favorably to chemotherapy. Hence, radiation therapy is now generally reserved for partially resected tumors and cases that failed to benefit from chemotherapy. At cross-sectional imaging, the tumor characteristically involves the cortical gray matter and frequently contains calcification. Robust enhancement is not a common feature and suggests transformation to a higher histologic grade. Advanced magnetic resonance imaging techniques and metabolic imaging play increasingly important roles in both pre- and postoperative assessment of these complex neoplasms.

Current Strategies in Treatment of Oligodendroglioma: Evolution of Molecular Signatures of Response

Oligodendroglioma frequently (≥ 70%) responds to radiation and chemotherapy, and is the first CNS neoplasm in which a genetic signature (1p and 19q deletion) has been associated with outcome within the context of large clinical trials. Current translational investigations focus on deletions or mutations of potential tumor suppressor genes, epigenetic alterations, amplification or mutation of growth factor and regulatory genes, and characterization of signaling events and regulatory protein expression. The most compelling data has involved 1p and 19q loss, which is observed in over 50% of anaplastic oligodendrogliomas. In two randomized phase III trials (Radiation Therapy Oncology Group 9402 and European Organisation for Research and Treatment of Cancer 26951), the addition of neoadjuvant or adjuvant procarbazine, lomustine, and vincristine (PCV; respectively) to radiotherapy did not produce superior survival as compared with radiotherapy alone. A modest increase in progression-free survival was observed with the addition of PCV, but at the cost of increased toxicity. Combined 1p and 19q loss identified a favorable prognostic group in both studies, which appeared to be independent of treatment arms. However, it is unclear whether these deletions represent surrogate markers of a favorable biologic tumor behavior, or are predictive of outcome after specific treatment. Currently, there is insufficient data to allow therapeutic decisions to be made solely on the basis of 1p and 19q gene deletion status. Future phase III trials are evaluating other chemotherapeutic and targeted agents, including temozolomide, and include correlative investigations of aberrant molecular events in these neoplasms, which may lead to future therapeutic strategies that are based on specific molecular signatures.

Proliferation (MIB-1 Expression) in Oligodendrogliomas

Expression of to nuclear antigen Ki-67 (MIB-1) has been linked to proliferative activity and prognosis in a variety of tumors. The authors assessed three techniques for quantitating MIB-1 (expression in oligodendrogliomas, correlating results with mitotic activity and prognosis. Formalin-fixed, paraffin-embedded sections of 38 oligodendrogliomas were immunostained using monoclonal MIB-l. Proliferation index (PI) was quantitated by visual estimation, CAS-200, and AC1S image analysis. MIB-1 expression and mitotic count were correlated with overall survival and recurrence (disease-free survival), defined clinically and radiographically as new tumor growth. Mean follow-up was 54 months (range 1-276). Mean PI quantitated by the three methods was statistically similar (Visual 10.5%, CAS-200, 12.2%, CAIS 11.2%). PI results by all three techniques correlated significantly with each other; visual and CAS-200 PI correlated with mitotic index. Overall and disease-free survivals were similar for patients with PIs above and below the mean by both image cytometric assays; visually estimated PIs below the mean, versus above the mean, correlated with improved disease-free survival. The authors show a significant correlation between MIB-1 PI using the visual method and recurrence in patients with oligodendrogliomas. The objectivity and speed of the image analysis systems make them an attractive alternative to visual estimation, and larger series should be analyzed for prognostic value.

Postoperative radiotherapy and chemotherapy in the management of oligodendroglioma: single institutional review of 88 patients

We retrospectively evaluate the prognostic factors affecting the local control, survival and the potential role of chemotherapy in the management of patients with oligodendroglioma. The medical records of 88 patients treated by postoperative external beam radiotherapy +/- chemotherapy at our institution between December 1993 and December 2002 were analyzed. Nine patients (10%) were treated with an accelerated fractionation scheme, while 79 patients were treated with conventional doses. The median RT dose was 54.8 +/- 2.58 Gy for low-grade tumors, and 58.7 +/- 2.46 Gy for high-grade tumors. PCV chemotherapy regimen was given to 18 patients; temozolamide was administered in three patients. Chemotherapy was not given concomitantly in any patients. The median follow-up was 56 months (range 7-134 months). The 5-year overall and progression-free survival rates for entire group were 86% and 79%, respectively. Patients with epilepsy at presentation had better 5-year overall survival (93% vs. 74%, P=0.04). High grade tumors had significantly lower overall survival rate. Age, presence of motor deficit at diagnosis and histological grade were found have a significant impact on progression-free survival. The 5-year overall and progression free survival rates of patients with high-grade tumors were 69%, 51% and 74%, 68% for chemotherapy and no-chemotherapy group, respectively (P=0.9 for OS, P=0.3 for PFS). In multivariate analysis no significant factor affecting the overall survival and progression-free survival was found. Chemotherapy given after postoperative radiotherapy in patients with oligodendroglioma did not improve survival in this retrospective study.

Oligodendroglioma: clinical study and survival analysis correlated with chromosomal anomalies

Object

Demonstration of the loss of chromosomes 1p and 19q in the presence of a brain neoplasm marks the emergence of genotype as a prognostic indicator. The authors report gene expression data for oligodendroglioma and correlate genotype with response to therapy. Gene expression subgroups may represent distinct types of disease.

Methods

Eighty-seven cases of supratentorial oligodendroglioma were selected from 145 cases treated in a single center between January 1990 and December 2001. Fluorescence in situ hybridization was used to determine the status of chromosomes 1p and 19q. Parameters evaluated included clinical data and radiological and histological features. Univariate and multivariate analyses were performed and a probability value less than 0.05 was considered significant.

The patients included 48 women and 39 men. The overall mean age at presentation was 45 years for women and 36 years for men (p = 0.006). The univariate analysis identified the following as favorable prognostic factors: younger patient age (p = 10−5), female sex (p = 0.0025), seizure as a presenting symptom (p = 10−5), normal clinical examination (p = 10−5), absence of lesion enhancement on neuroimaging studies (p = 0.0231), lack of histological necrosis (p = 0.0003), absence of mitoses (p = 0.0014), 1p and 19q deletions (p = 0.0001), absence of recurrence (p = 0.0021), and adjuvant radiotherapy and/or chemotherapy (p = 10−5). The multivariate analysis identified patient age (p = 10−5) and chromosomal anomalies (p = 0.002) as independently linked to survival. Three molecular subtypes emerged: oligodendroglioma with 1p and 19q deletions, oligodendroglioma demonstrating polysomia and a lack of meaningful response to radiotherapy or chemotherapy, and oligodendroglioma with no 1p-9q deletion in which partial response was seen.

Conclusions

According to our data, oligodendrogliomas could be divided into three molecular subtypes. Although chemotherapy seems efficient for managing this tumor, additional studies should be conducted to compare the efficacy of radiotherapy and chemotherapy.

Techniques to assess the proliferative potential of brain tumors

Assessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Many laboratories rely on mitotic figures to quantify the proliferative potential of brain tumors, but this conventional cellular proliferative index is subject to inter-observer variability and not consistently predictive for low-and high-grade tumors. Recent advancements in technology have made it possible to use proliferative indices as a standard supplement in pathology laboratories. Non-invasive tumor tissue measurements of cell proliferation can be performed using- bromodeoxyuridine labeling index (BrdU LI), flow cytometry (FCM), MIB-1 antibody to the Ki-67 antigen (MIB-1), proliferating cell nuclear antigen (PCNA), and argyrophilic nucleolar organizing regions (AgNOR). Each of these assays has been described in the literature with respect to its ability to predict tumor grade or outcome. At the present time MIB-1 and AgNOR are the simplest and most reliable of these techniques. In addition, advances in our understanding of the genetic alterations associated with proliferation promise to provide more specific markers of proliferative potential. Beyond the pathology laboratory, radiographic studies such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and most recently magnetic resonance spectroscopy (MRS) have been used as follow-up measures, assessing response to treatment and tumor recurrence, rather than as predictors of response to treatment. These radiographic tools, however, have the potential to provide an assessment of tumor proliferation without the need for invasive measures. In this article, we present a review of the current techniques utilized to understand the proliferative potential of brain tumors.

Immunohistochemical estimation of cell cycle entry and phase distribution in astrocytomas: applications in diagnostic neuropathology

An immunohistochemical method for assessing cell cycle phase distribution in neurosurgical biopsies would enable such data to be incorporated into diagnostic algorithms for the estimation of prognosis and response to adjuvant chemotherapy in glial neoplasms, without the requirement for flow cytometric analysis. Paraffin-embedded sections of intracerebral gliomas (n = 48), consisting of diffuse astrocytoma (n = 9), anaplastic astrocytoma (n = 8) and glioblastoma (n = 31), were analysed by immunohistochemistry using markers of cell cycle entry, Mcm-2 and Ki67, and putative markers of cell cycle phase, cyclins D1 (G1-phase), cyclin A (S-phase), cyclin B1 (G2-phase) and phosphohistone H3 (Mitosis). Double labelling confocal microscopy confirmed that the phase markers were infrequently coexpressed. Cell cycle estimations by immunohistochemistry were corroborated by flow cytometric analysis. There was a significant increase in Mcm-2 (P < 0.0001), Ki67 (P < 0.0001), cyclin A (P < 0.0001) and cyclin B1 (P = 0.002) expression with increasing grade from diffuse astrocytoma through anaplastic astrocytoma to glioblastoma, suggesting that any of these four markers has potential as a marker of tumour grade. In a subset of glioblastomas (n = 16) for which accurate clinical follow-up data were available, there was a suggestion that the cyclin A:Mcm-2 labelling fraction might predict a relatively favourable response to radical radiotherapy. These provisional findings, however, require confirmation by a larger study. We conclude that it is feasible to obtain detailed cell cycle data by immunohistochemical analysis of tissue biopsies. Such information may facilitate tumour grading and may enable information of prognostic value to be obtained in the routine diagnostic laboratory.

Place de la chimiothérapie et de la radiothérapie dans le traitement des oligodendrogliomes

Twenty years ago, the discovery of the chemosensitivity of anaplastic oligodendrogliomas considerably boosted interest for these tumors. In spite of difficulties for histological diagnosis, numerous studies on radiotherapy and chemotherapy for oligodendrogliomas appeared these last years. They allowed to detail the appropriate role for these therapeutics. For low grade oligodendrogliomas, radiotherapy delays the anaplastic transformation, but does not modify the overall survival; its indication has to be discussed particularly in the absence of clinical symptoms. Chemotherapy seems to be effective for low grade oligodendrogliomas as well as anaplastic tumors. However, phase III studies are necessary to clarify the contribution of chemotherapy for the treatment of low grade oligodendrogliomas, mainly in relation to radiotherapy. In anaplastic oligodendrogliomas, in spite of the lack of phase III studies, radiotherapy seems to be effective. Chemotherapy is clearly effective, but the most appropriate timing (neoadjuvant, adjuvant, at recurrence) is unknown. Results of current prospective studies are awaited. Recently, molecular genetic analysis, particularly the loss of 1p and 19q chromosomes appears to demonstrate a genetic influence on both prognosis and response to treatment.