Advances in the biology and treatment of oligodendrogliomas

Characterization and gene expression profiling in glioma cell lines with deletion of chromosome 19 before and after microcell-mediated restoration of normal human chromosome 19

Nearly 10% of human gliomas are oligodendrogliomas. Deletion of chromosome arm 19q, often in conjunction with deletion of 1p, has been observed in 65-80% of these tumors. This has suggested the presence of a tumor suppressor gene located on the 19q arm. Chromosome 19 deletion is also of interest due to the better prognosis of patients with deletion, including longer survival and better response to chemotherapy, compared with patients without deletion. Two glioma cell lines with deletion of 19q were used for chromosome 19 microcell-mediated transfer, to assess the effect of replacing the deleted segment. Complementation with chromosome 19 significantly reduced the growth rate of the hybrid cells compared with the parental cell lines. Affymetrix U133 Plus 2.0 Gene Chip analysis was performed to measure and compare the expression of the chromosome 19 genes in the chromosome 19 hybrid cell lines to the parental cell line. Probes were considered significantly different when a P value <0.01 was seen in all of the cell line comparisons. Of 345 probes within the commonly deleted 19q region, seven genes (APOE, RCN3, FLJ10781, SAE1, STRN4, CCDC8, and BCL2L12) were identified as potential candidate genes. RT-PCR analysis of primary tumor specimens showed that several genes had significant differences when stratified by tumor morphology or deletion status. This suggests that one or more of these candidates may play a role in glioma formation or progression.

Retrospective analysis of treatment outcome in 315 patients with oligodendroglial brain tumors

Although chemotherapy with procarbazine, lomustine and vincristine (PCV) is considered to be well tolerated, side effects frequently lead to dose reduction or even discontinuation of treatment of oligodendroglial brain tumors. The primary objective of the analysis was to retrospectively compare progression-free survival (PFS) after PCV vs. PC chemotherapy (without vincristine to avoid side effects). Patients were retrospectively identified from a database containing our patients between 1990 and 2003. For the selected cases, all histopathology reports were re-evaluated by a local neuropathologist. Based on the updated histology data, patients were included in the study if they had at least one histological diagnosis of an oligodendroglial tumor. PFS after start of PCV (n = 61) and PC (n = 84) chemotherapy identical (median 30 months). Multivariate analysis adjusting for prognostic imbalances favouring the PC group showed a minor, statistically non-significant benefit for PCV (hazard ratio 0.81, 95% confidence interval 0.53–1.25; p = 0.346). Younger age (< 50 y) was a statistically significant predictor of longer PFS. Significant advantages in terms of overall survival after first diagnosis of oligodendroglial tumor (OS, n = 315) were found for patients < 50 y (p < 0.001), oligodendrogliomas versus oligoastrocytomas (p = 0.002), and WHO°II vs. °III (p < 0.001). Three risk groups regarding OS were identified. Findings support the hypothesis that PC may be as effective as PCV chemotherapy, while avoiding the additonal risks of vincristine. Younger age, lower tumor grade and histology of an oligodendroglioma were identified to be favorable prognostic factors.

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.

Cerebral blood volume, genotype and chemosensitivity in oligodendroglial tumours

Introduction

The biological factors responsible for differential chemoresponsiveness in oligodendroglial tumours with or without the −1p/−19q genotype are unknown, but tumour vascularity may contribute. We aimed to determine whether dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) could distinguish molecular subtypes of oligodendroglial tumour, and examined the relationship between relative cerebral blood volume (rCBV) and outcome following procarbazine, lomustine and vincristine (PCV) chemotherapy.

Methods

Pretherapy rCBV was calculated and inter- and intraobserver variability assessed. Allelic imbalance in 1p36, 19q13, 17p13, 10p12–15, and 10q22–26 and p53 mutation (exons 5–8) were determined. rCBV was compared with genotype and clinicopathological characteristics (n=37) and outcome following PCV chemotherapy (n=33).

Results

1p/19q loss was seen in 6/9 grade II oligodendrogliomas, 6/14 grade II oligoastrocytomas, 4/4 grade III oligodendrogliomas, and 3/10 grade III oligoastrocytomas. rCBV measurements had good inter- and intraobserver variability, but did not distinguish histology subtype or grade. Tumours with 1p/19q loss had higher rCBV values (Student’s t-test P=0.001). Receiver operating characteristic analysis revealed a cut-off of 1.59 for identifying genotype (sensitivity 92%, specificity 76%). Tumours with high and low rCBV showed response to chemotherapy. The −1p/−19q genotype, but not rCBV, was strongly associated with response, progression-free and overall survival following PCV chemotherapy. Tumours with high rCBV and intact 1p/19q were associated with shorter progression-free and overall patient survival than those with intact 1p/19q and low rCBV or high rCBV and 1p/19q loss.

Conclusion

rCBV identifies oligodendroglial tumours with 1p/19q loss, but does not predict chemosensitivity. The prognostic significance of rCBV may differ in oligodendroglial tumours with or without the −1p/−19q genotype.

Fluorescence In Situ Hybridization (FISH) on Touch Preparations: A Reliable Method for Detecting Loss of Heterozygosity at 1p and 19q in Oligodendroglial Tumors

Combined loss of heterozygosity (LOH) on 1p and 19q is reported in 50% to 90% of oligodendroglial tumors and has emerged as a strong and favorable prognostic factor. Fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) are the most widely used techniques. The aim of this study was to evaluate the reliability of FISH to predict LOH at 1p and 19q when performed on touch preparations from 40 oligodendroglial tumors, even if the majority of the nuclei showed chromosomal imbalance. PCR was used as the gold standard. The presence of none or one target signal was reported as FISH-LOH, whereas all other losses were defined as FISH-imbalance. The sum of nuclei with FISH-LOH and imbalance was calculated in each case (FISH-sum) and cut-off values were defined as the mean FISH-sum value in controls plus 3 standard deviations; 27.7% for 1p and 33.2% for 19q. These corresponded well with the optimal cut-off values for our data, calculated using the minimum error rate classification procedure (35.6% for 1p and 33.1% for 19q). Concurrent FISH and PCR results were encountered in 95% for 1p and 87.5% for 19q. FISH-sum was the best and simplest discriminating variable for correct classification of LOH status. Under these conditions, even a dominant population of nuclei showing FISH-imbalance represented an LOH status in the tumor cells. FISH on touch preparations is a quick and reliable method for 1p/19q testing, does not require normal DNA and can be easily performed in an immunohistochemistry unit.

Serum IgE, tumor epidermal growth factor receptor expression, and inherited polymorphisms associated with glioma survival

In population-based glioma patients, we examined survival in relation to potentially pertinent constitutive polymorphisms, serologic factors, and tumor genetic and protein alterations in epidermal growth factor receptor (EGFR), MDM2, and TP53. Subjects were newly diagnosed adults residing in the San Francisco Bay Surveillance Epidemiology and End Results Area during 1991 to 1994 and 1997 to 1999 with central neuropathology review (n = 873). Subjects provided blood for serologic studies of IgE and IgG to four herpes viruses and constitutive specimens for genotyping 22 polymorphisms in 13 genes (n = 471). We obtained 595 of 697 astrocytic tumors for marker studies. We determined treatments, vital status, and other factors using registry, interview, medical record, and active follow-up data. Cox regressions for survival were adjusted for age, gender, ethnicity, study series, resection versus biopsy only, radiation, and chemotherapy. Using a stringent P < 0.001, glioma survival was associated with ERCC1 C8092A [hazard ratio (HR), 0.72; 95% confidence limits (95% CL), 0.60-0.86; P = 0.0004] and GSTT1 deletion (HR, 1.64; 95% CL, 1.25-2.16; P = 0.0004); glioblastoma patients with elevated IgE had 9 months longer survival than those with normal or borderline IgE levels (HR, 0.62; 95% CL, 0.47-0.82; P = 0.0007), and EGFR expression in anaplastic astrocytoma was associated with nearly 3-fold poorer survival (HR, 2.97; 95% CL, 1.70-5.19; P = 0.0001). Based on our and others' findings, we recommend further studies to (a) understand relationships of elevated IgE levels and other immunologic factors with improved glioblastoma survival potentially relevant to immunologic therapies and (b) determine which inherited ERCC1 variants or other variants in the 19q13.3 region influence survival. We also suggest that tumor EGFR expression be incorporated into clinical evaluation of anaplastic astrocytoma patients.

Survival rates and patterns of care for patients diagnosed with supratentorial low-grade gliomas: data from the SEER program, 1973-2001

BACKGROUND

Detailed population-based estimates of long-term survival as well as patterns of care for patients with low-grade gliomas examined by age at diagnosis, gender, and race have not been widely available.

METHODS

Time to death was examined among 2009 individuals diagnosed with a supratentorial low-grade glioma and reported to the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute from 1973-2001 using Kaplan-Meier estimation. A Cox proportional hazards model was used to assess the effect of age at diagnosis, race, gender, histology, anatomic location within the brain, first course of treatment, and year of diagnosis upon this risk.

RESULTS

The cumulative 5-, 10-, 15- and 20-year survival rates among all individuals initially diagnosed with a supratentorial low-grade glioma were 59.9% (95% confidence interval [95% CI], 57.6-62.2); 42.6% (95% CI, 39.9-45.2); 31.9% (95% CI, 29.0-34.8); and 26.0% (95% CI, 22.7-29.2), respectively. Improved survival was significantly associated with female gender (hazard ratio [HR], 0.84; 95% CI, 0.74-0.95), younger age, white race (HR, 0.70; 95% CI, 0.54-0.93), histology, and later year of diagnosis. Surgical treatment was associated with increased survival. The use of radiation therapy as a first course of treatment for these lesions has significantly decreased over time with the majority of patients receiving only surgery as a first course of treatment.

CONCLUSIONS

Data for patients diagnosed with low-grade gliomas revealed increasing survival times over the past 25 years with a subset of patients surviving for decades. Differences in survival by race, gender, histology, and first course of treatment were appreciated. These data suggested that the clinical course of low-grade glioma for some patients may be more encouraging than previously perceived and that the identification of this group of patients may allow refinement of current treatment protocols.

New concepts in surgery of WHO grade II gliomas: functional brain mapping, connectionism and plasticity – a review

Despite a recent literature supporting the impact of surgery on the natural history of low-grade glioma (LGG), the indications of resection still remain a matter of debate, especially because of the frequent location of these tumors within eloquent brain areas - thus with a risk to induce a permanent postoperative deficit. Therefore, since the antagonist nature of this surgery is to perform the most extensive glioma removal possible, while preserving the function and the quality of life, new concepts were recently applied to LGG resection in order to optimize the benefit/risk ratio of the surgery.First, due to the development of functional mapping methods, namely perioperative neurofunctional imaging and intrasurgical direct electrical stimulation, the study of cortical functional organization is currently possible for each patient - in addition to an extensive neuropsychological assessment. Such knowledge is essential because of the inter-individual anatomo-functional variability, increased in tumors due to cerebral plasticity phenomena. Thus, brain mapping enables to envision and perform a resection according to individual functional boundaries.Second, since LGG invades not only cortical but also subcortical structures, and shows an infiltrative progression along the white matter tracts, new techniques of anatomical tracking and functional mapping of the subcortical white matter pathways were also used with the goal to study the individual effective connectivity - which needs imperatively to be preserved during the resection.Third, the better understanding of brain plasticity mechanisms, induced both by the slow-growing LGG and by the surgery itself, were equally studied in each patient and applied to the surgical strategy by incorporating individual dynamic potential of reorganization into the operative planning. The integration of these new concepts of individual functional mapping, connectivity and plastic potential to the surgery of LGG has allowed an extent of surgical indications, an optimization of the quality of resection (neuro-oncological benefit), and a minimization of the risk of sequelae (benefit on the quality of life). In addition, such a strategy has also fundamental applications, since it represents a new door to the connectionism and cerebral plasticity.

Diagnostic, treatment, and demographic factors influencing survival in a population-based study of adult glioma patients in the San Francisco Bay Area

We compare survival estimates for population-based glioma cases by using two diagnostic coding schemes, (1) the International Classification of Diseases, Oncology, second edition (ICD-O-2) as reported by the Surveillance, Epidemiology, and End Results (SEER) program and (2) central neuropathology review diagnosis based on the World Health Organization II classification. In addition, among review categories, we estimate survival in relation to several patient demographic and treatment factors. Eligible cases included adults residing in the San Francisco Bay SEER Area with newly diagnosed, histologically confirmed glioma during the years 1991-1994 and 1997-1999. The study group included participating subjects for whom subsequent central neuropathology review confirmed glioma. We determined treatments, vital status, and other factors by using registry, interview, medical record, and active follow-up data. Survival differences between anaplastic astrocytoma (AA) and astrocytoma were apparent from review diagnoses (median months of survival for AA, 13.0 [95% CI, 9.9-19.5], and astrocytoma, 101.3 [95% CI lower limit, 42.1; upper limit not yet reached]), but not with ICD-O-2 diagnoses reported by SEER (median months of survival for AA, 16.6 [95% CI, 12.0-20.7], and astrocytoma, not otherwise specified, 17.2 [95% CI, 10.6-71.6]). This finding emphasizes the need for improvements in coding for nonglioblastoma astrocytomas to provide better population survival estimates. When review diagnosis was used, younger age and resection (vs. biopsy) were statistically significant for all histology groups analyzed by multivariable Cox proportional hazard models. Additional statistically significant variables were as follows: among 517 glioblastoma patients, radiation treatment and being married; among 105 AA patients, inclusion of chemotherapy in the initial treatment; and among 106 patients with nonanaplastic oligodendroglial tumors, college education. Further consideration of impact of marital status, education, and other social factors in glioma survival may be warranted.

Diffusely infiltrative low-grade gliomas in adults

Diffusely infiltrating low-grade gliomas (LGGs) include astrocytomas, oligodendrogliomas, and mixed oligoastrocytomas (WHO grade 2). Due to the routine use of magnetic resonance imaging, there is an increasing need to formulate treatment guidelines for patients with LGGs. However, there is little consensus about the optimal treatment strategy for diffusely infiltrative LGGs, and the clinical management of LGGs is one of the most controversial areas in neurooncology. Although the standard of care has not been established, several randomized trials are beginning to provide some answers. Furthermore, laboratory correlative studies are defining subsets of LGG that may identify patients with better prognoses and increased chance of responding to therapy. This article reviews the most recent data regarding the treatment of LGG, emphasizing evidenced based approaches from current clinical trials.

Comparative genomic hybridization pattern of non-anaplastic and anaplastic oligodendrogliomas – A meta-analysis

Many oligodendrogliomas (ODG) have been investigated by comparative genomic hybridization (CGH). To visualize characteristic aberration profiles of non-anaplastic in a comparison with anaplastic ODGs, we performed a meta-analysis of the CGH results of all 89 cases published so far. Therefore, we expanded all given aberrations to the maximum of 850 GTG band resolution. The frequencies of each chromosomal band affected by a genetic imbalance were calculated for WHO grades II and III separately. In non-anaplastic ODGs, -1p and -19q were the most prominent aberrations. In anaplastic ODGs, +7, -4q, -9p, -10, and -15q emerged additionally. We could confirm the existence of three disjunct genetically defined subgroups of ODGs, characterized by -1p/-19q (n=58, 65%, subgroup A), +7/-10 (n=6, 7%, subgroup B) or the absence of either of the two patterns (n=25, 28%, subgroup C). Interestingly, we found a unique aberration pattern in subgroup C (-1p31, -4q, -11p15, -18q, -22q, +17p, +17q) that was different from subgroups A and B, which could indicate a unique molecular carcinogenetic pathway of this ODG subset. Scrutinizing published putative progression markers of ODG, we found that only +7, -10, and -15q significantly correlated with a higher grade of malignancy. Summing up, the expansion of the CGH results to the 850 GTG band resolution enabled a meta-analysis to visualize WHO grade-specific aberration profiles in ODG for the first time.

[Results of the Sainte-Anne - Lyons series of 318 oligodendroglioma in adults]

INTRODUCTION

Incidence of cerebral oligodendrogliomas is increasing because of better recognition made possible by improved classifications. We studied a homogeneous series using the Sainte-Anne grading scale in order to better understanding the history of these tumors with or without treatment and to assess prognosis and associated factors.

PATIENTS AND METHODS

A retrospective series of 318 adult patients with oligodendroglioma (OLG) treated at Hôpital Sainte-Anne, Paris (SA) and Hôpital Neurologique, Lyons (L) between 1984 and 2003 was analyzed: 182 grade A OLG (SA + L), 136 grade B among which a homogenous series of 98 (SA) were included. For grade A: age at diagnosis ranged from 21 to 70 (mean: 41), sex ratio was 1.28. For grade B: age at diagnosis ranged from 12 to 75 (mean: 45.5), sex-ratio was 1.58. The main first symptoms were: epilepsy (A: 91.5%; B: 76%), intracranial hypertension (A: 7.9%; B: 14.6%), neurological deficit (A: 5.1%; B: 17.7%). The most frequent locations were: frontal, insular and central for both A and B. Mean size was 55 mm for grade A, 62 mm for B. Calcifications were found in 20% of A, 48.5% of B. No tumor was enhanced on imaging (CT/MRI) in grade A, all but 7 in grade B. All patients underwent surgery either for biopsy (A: 47.2%; B: 53%), or removal which was partial (A: 26.4% vs B: 19.4%) or extended (A: 36.3% vs B: 37.8%). Fifty-six patients underwent 2 procedures and 12 three procedures. Radiotherapy was performed in 76.9% of grade A, and 91% of B patients, in the immediate postoperative period for 71% A and 82.7% B. Chemotherapy was delivered for 36% of grade A (in the event of transformation to grade B or failure of radiotherapy) and 67.5% of B patients. Among grade A tumors, 38% transformed into grade B within a mean delay of 51 months with a mean follow-up of 78 months.

RESULTS

Median survival was 136 months for grade A and 52 for grade B. Survival at 5, 10 and 15 was 75.5%, 51% and 22.4% for grade A vs 45.2%, 31.3% and 0% for grade B respectively. In univariate and multivariate analysis, grade A survival was associated with age at diagnosis, tumor size, large removal and response to radiotherapy. Grade B survival was associated with age at diagnosis, wide removal and sharply defined limits of the tumor on imaging.

CONCLUSIONS

Analysis of both published data and this series underlines many prognostic parameters. It shows that OLG are heterogeneous tumors even in each grade (A and B). Treatment should consequently progress towards more targeted procedures for patients mainly with postoperative radiotherapy and chemotherapy.

Surgery for malignant gliomas: mechanistic reasoning and slippery statistics

Current surgical treatment of malignant gliomas largely depends on mechanistic reasoning and data collected in non-randomised studies. Technological advance has enabled more accurate resection of tumours and preservation of eloquent brain areas but ethical considerations have restricted randomised trials on the efficacy of surgery to one small trial that found a 3 month survival advantage for patients over age 65 years who received surgery and interim analysis of a larger trial. There is an argument for surgery as a palliative measure in patients with symptoms caused by mechanisms that are surgically remediable. Whether there is any survival advantage from surgery in patients other than those with immediately life-threatening, surgically remediable complications, such as raised intracranial pressure, is unclear. The available data show that if such an advantage does exist, it is modest at best. Adjuvant treatments given surgically are being studied. Chemotherapy wafers are the most prominent of the adjuvant treatments but the evidence available is insufficient to recommend their use in routine practice. In this review we examine the prevailing mechanistic model and observational data; we assess how these are applied and the priorities they indicate for future research.

MRS of oligodendroglial tumors: Correlation with histopathology and genetic subtypes

BACKGROUND

Oligodendroglial neoplasms with combined loss of chromosomes 1p and 19q may have a good prognosis and respond to procarbazine-lomustine (CCNU)-vincristine (PCV) chemotherapy.

OBJECTIVE

To determine whether single voxel magnetic resonance spectroscopy (SV-MRS) obtained through routine clinical practice distinguishes between histopathologic and genetic subtypes of oligodendroglial tumors.

METHODS

Forty-eight patients with oligodendroglial tumors (19 oligodendrogliomas and 29 oligoastrocytomas) underwent molecular genetic analysis to determine allelic imbalance in chromosomes 1p36 and 19q13. SV-MRS was obtained pretherapy to determine tumor metabolite ratios.

RESULTS

Grade III oligodendroglial tumors had higher choline (Mann-Whitney; p = 0.002), methyl lipid (Mann-Whitney; p = 0.002), and combined methylene lipid and lactate ratios (Mann-Whitney; p < 0.001) than grade II tumors. Lactate did not distinguish between tumor types (Fisher exact test; p = 0.342) or grade (Fisher exact test; p = 0.452). There were no significant associations when tumors were analyzed according to histopathology or genetic subtypes.

CONCLUSION

As a noninvasive diagnostic tool used in routine clinical practice, SV-MRS has the potential benefit of determining oligodendroglial tumor grade but not subtypes classified by histopathology or molecular genetics. MRS may be useful for determining the timing of therapy but is unlikely to predict chemosensitivity.