Prognostic stratification of patients with anaplastic gliomas according to genetic profile

BACKGROUND: There is a need to improve the current, controversial, and poorly reproducible classification of anaplastic gliomas, which represent a highly heterogeneous entity in terms of survival. METHODS: The impact of the most common genetic alterations on survival was investigated based on 156 anaplastic gliomas: Among the patients who were included, the gender ratio was 1.32, the median age was 45.5 years (range, 20-83 years), and the median Karnofsky performance status was 70 (range, 40-100). Genetic analysis included a search for loss of heterozygosity (LOH) on chromosomes 1p and 19q; amplification of chromosomes 9p and 10q and of the epidermal growth factor receptor (EGFR), cyclin-dependent kinase 4 (CDK4) and mouse double-minute (MDM2) genes; and p53 expression. RESULTS: The median survival was 33.5 months, and the median progression-free survival was 15.8 months. In a univariate analysis, LOH on 1p and 19q was correlated with longer survival, whereas p53 expression, LOH on 9p, LOH on 10q, amplified EGFR, and deleted CDKN2A were correlated with shorter survival. LOH on 1p and 19q were associated with oligodendrogliomas, LOH on 10q was related to EGFR amplification, and LOH on 1p and 19q was mutually exclusive with EGFR amplification and LOH on 10q. In a multivariate analysis, the significant prognostic factors were age, histology, LOH on 1p and 19q, and P16/CDKN2A deletion. Recursive partitioning analysis (RPA) divided the whole group hierarchically into 3 distinct prognostic subgroups: Group A with 1p19q codeletion (median survival, 98 months), Group B with EGFR amplification (median survival, 17 months), and Group CC (median survival, 31 months), providing a basis for a genetically based prognostic subclassification for patients with Grade III gliomas. CONCLUSIONS: The search for 1p19q codeletion and EGFR receptor amplification provides a simple, clinically relevant prognostic subclassification of grade III gliomas.     

Genetic analyses for predictors of radiation response in glioblastoma

PURPOSE: Radiotherapy (RT) for patients with glioblastoma improves survival and is recommended for nearly all patients with this diagnosis. However, the response to RT is variable in this patient population. Prior studies have suggested that underlying genetic alterations in the tumor may account for some of this treatment-related heterogeneity. It has been previously reported that epidermal growth factor receptor (EGFR) gene amplification and TP53 mutation correlate with the response to RT in patients with glioblastoma. METHODS AND MATERIALS: We sought to identify molecular markers that could predict the response to RT, progression-free survival after RT, and overall survival among 75 glioblastoma patients treated with RT at a single institution. Genetic analyses assessed EGFR amplification, TP53 mutations, CDKN2A/p16 deletion, and losses of chromosomes 1p, 10q, and 19q. RESULTS: Unlike previous reports, no association of EGFR amplification with response to RT, progression-free survival, or overall survival was found. Moreover, no association was found between these endpoints and the other genetic alterations assayed (TP53 mutation, CDKN2A/p16 deletion, loss of heterozygosity 1p, loss of heterozygosity 10q, and loss of heterozygosity 19q). However, in accordance with recent observations that the prognostic effects of genetic alterations in glioblastoma may depend on patient age, we observed age-dependent prognostic effects of TP53 and CDKN2A/p16 alterations in our patient population. For patients > or = 57 years old, those harboring TP53 mutations had a decreased overall survival compared with patients without TP53 mutations. Similarly, deletion of CDKN2A/p16 in patients > or = 57 years was associated with decreased progression-free survival after RT and a trend toward a shorter time to progression after RT compared with similar patients without the deletion. CONCLUSION: These data contrast with previous studies regarding the significant prognostic effect of EGFR with respect to RT response. Although our observations regarding the age-dependent prognostic effects of TP53 and CDKN2A/p16 are consistent with a prior report regarding these alterations, the present results should be considered preliminary, given the small sample size.     

PTEN mutation, EGFR amplification, and outcome in patients with anaplastic astrocytoma and glioblastoma multiforme

BACKGROUND: Survival of patients with anaplastic astrocytoma is highly variable. Prognostic markers would thus be useful to identify clinical subsets of such patients. Because specific genetic alterations have been associated with glioblastoma, we investigated whether similar genetic alterations could be detected in patients with anaplastic astrocytoma and used to identify those with particularly aggressive disease. METHODS: Tissue specimens were collected from 174 patients enrolled in Mayo Clinic Cancer Center and North Central Cancer Treatment Group clinical trials for newly diagnosed gliomas, including 63 with anaplastic astrocytoma and 111 with glioblastoma multiforme. Alterations of the EGFR, PTEN, and p53 genes and of chromosomes 7 and 10 were examined by fluorescence in situ hybridization, semiquantitative polymerase chain reaction, and DNA sequencing. All statistical tests were two-sided. RESULTS: Mutation of PTEN, amplification of EGFR, and loss of the q arm of chromosome 10 were statistically significantly less common in anaplastic astrocytoma than in glioblastoma multiforme (P =.033, P =.001, and P<.001, respectively), and mutation of p53 was statistically significantly more common (P<.001). Univariate survival analyses of patients with anaplastic astrocytoma identified PTEN (P =.002) and p53 (P =.012) mutations as statistically significantly associated with reduced and prolonged survival, respectively. Multivariate Cox analysis of patients with anaplastic astrocytoma showed that PTEN mutation remained a powerful prognostic factor after adjusting for patient age, on-study performance score, and extent of tumor resection (hazard ratio = 4.34; 95% confidence interval = 1.82 to 10.34). Multivariate classification and regression-tree analysis of all 174 patients identified EGFR amplification as an independent predictor of prolonged survival in patients with glioblastoma multiforme who were older than 60 years of age. CONCLUSION: PTEN mutation and EGFR amplification are important prognostic factors in patients with anaplastic astrocytoma and in older patients with glioblastoma multiforme, respectively.     

Prognostic impact of molecular markers in a series of 220 primary glioblastomas

BACKGROUND: In contrast to oligodendrogliomas, molecular predictors of prognosis have not been consistently found in glioblastomas. However, genetic studies show that glioblastomas consist of several genetic subtypes and raise the possibility that molecular alterations could be predictive of survival. METHODS: A search for loss of heterozygosity (LOH) on chromosome 1p, 9p, 10q, 19q, EGFR (epidermal growth factor receptor), CDK4, and MDM2 (mouse double minute) amplifications, CDKN2A (INK4A/ARF) homozygous deletions, p53 expression, was performed in a series of 220 primary glioblastomas. The molecular alterations were then correlated with each other to identify distinct molecular pathways and with clinical parameters and the course of the disease to identify prognostic markers. RESULTS: Nonrandom associations were found between EGFR amplification and LOH10q, LOH9p, and INK4A/ARF deletion, LOH1p and LOH19q, and MDM2 and CDK4 amplification, whereas mutual exclusions were found between p53 expression and EGFR amplification, LOH 9p/INK4A/ARF homozygous deletion, and MDM2 and CDK4 amplification. Age (P = 4.10(-5)) and performance status (P = .003) were the main predictors of outcome. In contrast, molecular markers were of limited impact: MDM2 amplification correlated with poor outcome on both univariate and multivariate analysis (P = .01) and EGFR amplification with good prognosis on multivariate analysis (P = .02). CONCLUSION: Despite their limited prognostic impact, the genetic markers investigated here outline distinct molecular pathways involved in glioblastoma tumorigenesis and warrant broader molecular screening.     

Molecular analysis of anaplastic oligodendroglial tumors in a prospective randomized study: A report from EORTC study 26951

Recent studies have shown that the clinical outcome of anaplastic oligodendroglial tumors is variable, but also that the histological diagnosis is subject to interobserver variation. We investigated whether the assessment of 1p/19q codeletion, polysomy of chromosome 7, epidermal growth factor receptor (EGFR) gene amplification (EGFR^amp), and loss of chromosome 10 or 10q offers additional prognostic information to the histological diagnosis and would allow molecular subtyping. For this study, we used the clinical data and tumor samples of the patients included in multicenter prospective phase III European Organisation for Research and Treatment of Cancer (EORTC) study 26951 on the effects of adjuvant procarbazine, chloroethyl cyclohexylnitrosourea (lomustine), and vincristine chemotherapy in anaplastic oligodendroglial tumors. Fluorescence in situ hybridization was used to assess copy number aberrations of chromosome 1p, 19q, 7, 10, and 10q and EGFR. Three different analyses were performed: on all included patients based on local pathology diagnosis, on the patients with confirmed anaplastic oligodendroglial tumors on central pathology review, and on this latter group but after excluding anaplastic oligoastrocytoma (AOA) with necrosis. As a reference set for glioblastoma multiforme (GBM), patients from the prospective randomized phase III study on GBM (EORTC 26981) were used as a benchmark. In 257 of 368 patients, central pathology review confirmed the presence of an anaplastic oligodendroglial tumor. Tumors with combined 1p and 19q loss (1p^loss19q^loss) were histopathologically diagnosed as anaplastic oligodendroglioma, were more frequently located in the frontal lobe, and had a better outcome. Anaplastic oligodendroglial tumors with EGFR^amp were more frequently AOA, were more often localized outside the frontal lobe, and had a survival similar to that for GBM. Survival of patients with AOA harboring necrosis was in a similar range as for GBM, while patients with AOA with only endothelial proliferation had better overall survival. In univariate analyses, all molecular factors except loss of 10q were of prognostic significance, but on multivariate analysis a histopathological diagnosis of AOA, necrosis, and 1p^loss19q^loss remained independent prognostic factors. AOA tumors with necrosis are to be considered WHO grade IV tumors (GBM). Of all molecular markers analyzed in this study, especially loss of 1p/19q carried prognostic significance, while the others contributed little prognostic value to classical histology.     

Identification of genomic aberrations associated with shorter overall survival in patients with oligodendroglial tumors

Deletions on chromosomes 1p and 19q are associated with favorable prognosis in patients with oligodendroglial tumors. The aim of our study was to identify additional genomic aberrations linked to patient survival. We performed a genome-wide screen for genomic imbalances by comparative genomic hybridization on tumors from 70 patients, including 40 oligodendrogliomas, 30 oligoastrocytomas (21 WHO grade II tumors, 49 WHO grade III tumors). Data were correlated with overall patient survival (OS, median follow-up: 5.8 years). The most frequent aberrations were losses on chromosome 19q (64%), 1p (59%), 9p (26%), 4q (21%), 10q (19%), 18q (17%); gains on 7q (24%), 19p (19%), 7p (17%). In univariate analyses, combined 1p/19q and 19q loss were significantly associated with longer OS, and gains on 7, 8q, 19q, 20, losses on 9p, 10, 18q, Xp with shorter OS. Multivariate analyses showed the most significant prognostic factors for OS of patients with any oligodendroglial tumor to be WHO grade [odds ratio (OR) 8], 7p gain (OR 6), 9p loss (OR 3); for OS of patients with anaplastic tumors to be 7p gain (OR 10), 8q gain (OR 5), 18q loss (OR 3). Patients with anaplastic oligodendroglial tumors containing one or more prognostically unfavorable genomic aberration had a poor outcome independent of the 1p/19q status. In summary, we identified several independent genomic markers of shorter survival in patients with oligodendroglial tumors. Thus, molecular diagnostic testing, which is usually restricted to 1p/19q deletion analysis, may need to be refined by additionally assessing the prognostically unfavorable genomic aberrations identified.     

Molecular and clinical analysis of glioblastoma with an oligodendroglial component (GBMO)

The genetic and clinical features of glioblastoma with an oligodendroglial component (GBMO), pathologically defined as anaplastic oligo-astrocytoma with necrosis, remain unclear. We investigated the correlation between genetic alterations and clinical outcomes in 19 GBMO patients we have encountered since 1997. Using single nucleotide polymorphism oligonucleotide genomic (SNP) microarrays, we analyzed gene amplification, loss of heterozygosity (LOH), and homozygous deletions in their whole genome. We also analyzed their overall survival (OS). Pathological studies revealed the presence of calcification in 11 and of a cyst in 9 of the 19 patients. Whole-genome analysis using SNP microarrays revealed LOH of chromosome 10 in 11, EGFR amplification in 8, 9p21 (INK4 locus) deletion in 12, PDGFR amplification in 2, and LOH of 1p19q in 2 patients. Median OS was 14?months (average 22.8?months). The pattern of genetic alterations was similar in GBMO and glioblastoma multiforme (GBM) patients, and the clinical outcomes were similar in GBMO and GBM patients.     

Distinct responses of xenografted gliomas to different alkylating agents are related to histology and genetic alterations

A series of 12 human gliomas was established as xenografts in nude mice and used to evaluate the relationship between histology, genetic parameters, and response to alkylating agents. Eight were high-grade oligodendroglial tumors, and four were glioblastoma. They were characterized for their genetic alterations, including those considered as "early" alterations, namely loss of chromosome 1 +/- loss of chromosome 19q, TP53 mutation, and those considered as "late" alterations, namely loss of chromosome 10, loss of chromosome 9p, EGFR genomic amplification, PTEN mutation, CDKN2A homozygous deletion, and telomerase reactivation. Chemosensitivity of xenografts to four alkylating agents, temozolomide (42 mg/kg, days 1-5, p.o.), 1,3-bis(2-chloroethyl)-1-nitrosourea (5 mg/kg, day 1, i.p.), Ifosfamide (90 mg/kg, days 1-3, i.p.), and carboplatin (66 mg/kg, day 1, i.p.) was tested by administration of drugs to tumor-bearing mice. Although each tumor presented an individual response pattern, glioblastoma had a lower chemosensitivity than oligodendrogliomas, and temozolomide was the most effective drug. Deletion of 1p +/- 19q was associated with higher chemosensitivity, whereas late molecular alterations, particularly EGFR amplification, were associated with chemoresistance. These results suggest that the combined use of histology and molecular markers should eventually be helpful selecting the most appropriate agents for treatment of malignant oligodendrogliomas and astrocytomas.     

Chromosomal abnormalities in human glioblastomas: gain in chromosome 7p correlating with loss in chromosome 10q

Various genomic alterations have been detected in glioblastoma. Chromosome 7p, with the epidermal growth factor receptor locus, together with chromosome 10q, with the phosphatase and tensin homologue deleted in chromosome 10 and deleted in malignant brain tumors-1 loci, and chromosome 9p, with the cyclin-dependent kinase inhibitor 2A locus, are among the most frequently damaged chromosomal regions in glioblastoma. In this study, we evaluated the genetic status of 32 glioblastomas by comparative genomic hybridization; the sensitivity of comparative genomic hybridization versus differential polymerase chain reaction to detect deletions at the phosphatase and tensin homologue deleted in chromosome 10, deleted in malignant brain tumors-1, and cyclin-dependent kinase inhibitor 2A loci and amplifications at the cyclin-dependent kinase 4 locus; the frequency of genetic lesions (gain or loss) at 16 different selected loci (including oncogenes, tumor-suppressor genes, and proliferation markers) mapping on 13 different chromosomes; and the possible existence of a statistical association between any pair of molecular markers studied, to subdivide the glioblastoma entity molecularly. Comparative genomic hybridization showed that the most frequent region of gain was chromosome 7p, whereas the most frequent losses occurred on chromosomes 10q and 13q. The only statistically significant association was found for 7p gain and 10q loss.     

Comparative genetic patterns of glioblastoma multiforme: potential diagnostic tool for tumor classification

Cytogenetic and molecular genetic studies of glioblastoma multiforme (GBM) have shown that the most frequent alterations are gains of chromosome 7, losses of 9p loci and chromosome 10, and gene amplification, primarily of the epidermal growth factor receptor (EGFR) gene. Although this profile is potentially useful in distinguishing GBM from other tumor types, the techniques used tend to be labor intensive, and some can detect only gains or losses of genetic loci. Comparative genomic hybridization (CGH) is a powerful technique capable of identifying both gains and losses of DNA sequences. The present study compares the CGH evaluation of 22 GBM with classic cytogenetics, loss of heterozygosity by allelotyping, and gene amplification by Southern blot analysis to determine the reliability of CGH in the genetic characterization of GBM. The CGH and karyotypic data were consistent in showing gain of chromosome 7 accompanied by a loss of chromosome 10 as the most frequent abnormality, followed by a loss of 9p in 17 of 22 GBM cases. Loss of heterozygosity of chromosomes 10 (19/22) and 9p (9/22) loci confirmed the underrepresentation by CGH. Genomic amplifications were observed by CGH in 5 of the 10 cases where gene amplification was detected by Southern blot analysis. The data show that CGH is equally reliable, compared with the more established genetic methods, for recognizing the prominent genetic alterations associated with GBM and support its use as a plausible adjunct to glioma classification.     

Numerical and structural aberrations in advanced neuroblastoma tumours by CGH analysis; survival correlates with chromosome 17 status

Rapid tumour progression in neuroblastoma is associated with MYCN amplification, deletion of the short arm of chromosome 1 and gain of 17q. However, patients with advanced disease without MYCN amplification and/or 1p deletion have a very poor outcome too, which suggests other genetic defects may predict an unfavourable prognosis. We employed CGH to study 22 tumours of patients at stages 3 and 4 over one year of age (6 and 16 cases respectively). Patients were divided in groups (A) long-term survivors and (B) short-term survivors. CGH showed a total of 226 chromosome imbalances (110 in group A and 116 in group B). The neuroblastoma cells of long-term survivors showed a preponderance of numerical aberrations (54%vs 43%); particularly gains of entire chromosomes 1 (P< 0.03), 7 (P< 0.04) and 19 (P< 0.05). An extra copy of 17 was detected in 6/8 (75%) samples of group A and only 1/14 (7%) samples of group B (P< 0.002). Conversely, tumours of patients who died from disease progression displayed a higher frequency of structural abnormalities (43%vs 35%), including loss of 1p, 9p, 11q, 15q and 18q and gain of 12q, although the difference was not significant (P = 0.24). Unbalanced gain of 17q was detected in 8/14 (57%) tumours of group B and only 1/8 (13%) tumours of group A (P< 0.05). The peculiar genetic difference observed in the tumours of long and short-term survivors may have prognostic relevance.     

Epithelial and pseudoepithelial differentiation in glioblastoma and gliosarcoma: a comparative morphologic and molecular genetic study

BACKGROUND: Glioblastomas exhibit a remarkable tendency toward morphologic diversity. Although rare, pseudoepithelial components (adenoid or epithelioid) or true epithelial differentiation may occur, posing a significant diagnostic challenge. METHODS: Hematoxylin and eosin-stained slides were reviewed, and immunohistochemistry and fluorescence in situ hybridization were performed. RESULTS: The patients included 38 men and 20 women. The median age at diagnosis was 57 years (interquartile range [IQR], 50 years-67 years), and the median overall survival was 7 months (IQR, 4 months-11 months). "Adenoid" glioblastomas (A-GBM) predominated (48%). True epithelial glioblastomas (TE-GBM) were next most frequent based on morphology and immunohistochemistry (35%), followed by epithelioid glioblastomas (E-GBM) (17%). Overall, 25 (43%) tumors featured a sarcomatous component. Molecular cytogenetic abnormalities identified by fluorescent in situ hybridization in A-GBM, E-GBM, and TE-GBM, respectively, included p16 deletion/-9 (60%, 71%, 64%); chromosome 10 loss (40%, 63%, 57%), chromosome 7 gain without EGFR amplification (70%, 38%, 40%), EGFR amplification (10%, 50%, 27%), PTEN deletion (10%, 25%, 29%), PDGFRA amplification (10%, 25%, 0%), and RB1 deletion/-13q (50%, 0%, 14%). Abnormalities identified by immunohistochemistry included p21 immunonegativity (60%, 25%, 93%), which was most frequent in TE-GBM (P = .008), strong nuclear p53 staining (29%, 29%, 41%), strong membranous staining for epidermal growth factor receptor (EGFR) (21%, 63%, 19%), which was most frequent in E-GBM (P = .03), and an increased frequency of p27 immunonegativity in gliosarcomas (15% negative, 85% focal) compared with tumors without sarcoma (38% strongly positive) (P = .009). CONCLUSIONS: Pseudoepithelial and true epithelial morphology are rare phenomena in GBM and may be associated with a similar poor prognosis. These tumors demonstrate proportions of molecular genetic abnormalities varying somewhat from conventional GBM.     

BAC array CGH distinguishes mutually exclusive alterations that define clinicogenetic subtypes of gliomas

The pathological classification of gliomas constitutes a critical step of the clinical management of patients, yet it is frequently challenging. To assess the relationship between genetic abnormalities and clinicopathological characteristics, we have performed a genetic and clinical analysis of a series of gliomas. A total of 112 gliomas were analyzed by comparative genomic hybridization on a BAC array with a 1 megabase resolution. Altered regions were identified and correlation analysis enabled to retrieve significant associations and exclusions. Whole chromosomes (chrs) 1p and 19q losses with centromeric breakpoints and EGFR high level amplification were found to be mutually exclusive, permitting identification of 3 distinct, nonoverlapping groups of tumors with striking clinicopathological differences. Type A tumors with chrs 1p and 19q co-deletion exhibited an oligodendroglial phenotype and a longer patient survival. Type B tumors were characterized by EGFR amplification. They harbored a WHO high grade of malignancy and a short patient survival. Finally, type C tumors displayed none of the previous patterns but the presence of chr 7 gain, chr 9p deletion and/or chr 10 loss. It included astrocytic tumors in patients younger than in type B and whose prognosis was highly dependent upon the number of alterations. A multivariate analysis based on a Cox model shows that age, WHO grade and genomic type provide complementary prognostic informations. Finally, our results highlight the potential of a whole-genome analysis as an additional diagnostic in cases of unclear conventional genetic findings.     

Genomic aberrations associated with outcome in anaplastic oligodendroglial tumors treated within the EORTC phase III trial 26951

Despite similar morphological aspects, anaplastic oligodendroglial tumors (AOTs) form a heterogeneous clinical subgroup of gliomas. The chromosome arms 1p/19q codeletion has been shown to be a relevant biomarker in AOTs and to be perfectly exclusive from EGFR amplification in gliomas. To identify new genomic regions associated with prognosis, 60 AOTs from the EORTC trial 26951 were analyzed retrospectively using BAC-array-based comparative genomic hybridization. The data were processed using a binary tree method. Thirty-three BACs with prognostic value were identified distinguishing four genomic subgroups of AOTs with different prognosis (p < 0.0001). Type I tumors (25%) were characterized by: (1) an EGFR amplification, (2) a poor prognosis, (3) a higher rate of necrosis, and (4) an older age of patients. Type II tumors (21.7%) had: (1) loss of prognostic BACs located on 1p tightly associated with 19q deletion, (2) a longer survival, (3) an oligodendroglioma phenotype, and (4) a frontal location in brain. Type III AOTs (11.7%) exhibited: (1) a deletion of prognostic BACs located on 21q, and (2) a short survival. Finally, type IV tumors (41.7%) had different genomic patterns and prognosis than type I, II and III AOTs. Multivariate analysis showed that genomic type provides additional prognostic data to clinical, imaging and pathological features. Similar results were obtained in the cohort of 45 centrally reviewed?Cvalidated cases of AOTs. Whole genome analysis appears useful to screen the numerous genomic abnormalities observed in AOTs and to propose new biomarkers particularly in the non-1p/19q codeleted AOTs.     

A t(1;19)(q10;p10) mediates the combined deletions of 1p and 19q and predicts a better prognosis of patients with oligodendroglioma

Combined deletion of chromosomes 1p and 19q is associated with improved prognosis and responsiveness to therapy in patients with anaplastic oligodendroglioma. The deletions usually involve whole chromosome arms, suggesting a t(1;19)(q10;p10). Using stem cell medium, we cultured a few tumors. Paraffin-embedded tissue was obtained from 21 Mayo Clinic patients and 98 patients enrolled in 2 North Central Cancer Treatment Group (NCCTG) low-grade glioma trials. Interphase fusion of CEP1 and 19p12 probes detected the t(1;19). 1p/19q deletions were evaluated by fluorescence in situ hybridization. Upon culture, one oligodendroglioma contained an unbalanced 45,XX,t(1;19)(q10;p10). CEP1/19p12 fusion was observed in all metaphases and 74% of interphase nuclei. Among Mayo Clinic oligodendrogliomas, the prevalence of fusion was 81%. Among NCCTG patients, CEP1/19p12 fusion prevalence was 55%, 47%, and 0% among the oligodendrogliomas, mixed oligoastrocytomas, and astrocytomas, respectively. Ninety-one percent of NCCTG gliomas with 1p/19q deletion and 12% without 1p/19q deletion had CEP1/19p12 fusion (P < 0.001, chi(2) test). The median overall survival (OS) for all patients was 8.1 years without fusion and 11.9 years with fusion (P = 0.003). The median OS for patients with low-grade oligodendroglioma was 9.1 years without fusion and 13.0 years with fusion (P = 0.01). Similar significant median OS differences were observed for patients with combined 1p/19q deletions. The absence of alterations was associated with a significantly shorter OS for patients who received higher doses of radiotherapy. Our results strongly suggest that a t(1;19)(q10;p10) mediates the combined 1p/19q deletion in human gliomas. Like combined 1p/19q deletion, the 1;19 translocation is associated with superior OS and progression-free survival in low-grade glioma patients.     

Screening of genomic imbalances in glioblastoma multiforme using high-resolution comparative genomic hybridization

Comparative genomic hybridization (CGH) is a molecular cytogenetic technique that allows the genome-wide analysis of DNA sequence copy number differences. We applied conventional CGH and the recently developed high-resolution CGH (HR-CGH) to tumour samples from 18 patients with glioblastoma multiforme (GBM) in order to compare the sensitivity of CGH and HR-CGH in the screening of chromosomal abnormalities. The abnormalities were studied in topologically different central and peripheral tumour parts. A total of 78 different changes were observed using CGH (0-16 per tumour, median 3.5) and 154 using HR-CGH (0-21 per tumour, median 6). Using HR-CGH, losses were more frequent than gains. The representation of the most prominent changes revealed by both methods was similar and was comprised of the amplification of 7q12 and 12q13-q15, the gain of 7, 3q and 19, and the loss of 10, 9p, and 13q. However, HR-CGH detected certain other abnormalities (the loss of 6, 14q, 15q and 18q, and the gain of 19), which were rarely revealed by CGH. Using HR-CGH, the numbers and types of chromosomal changes detected in the central and peripheral parts of GBM were almost the same. The loss of chromosomes 10 and 9p and the gain of chromosomes 7 and 19 were the most frequent chromosomal alterations in both tumour parts. Our results from the GBM analysis show that HR-CGH technology can reveal new, recurrent genetic alterations involving the genes known to participate in tumorigenesis and in the progression of several human malignancies, thus allowing for a more accurate genetic characterization of these tumours.     

Molecular pathogenesis of malignant gliomas.

De novo glioblastomas develop in older patients without prior clinical history of less malignant tumors. Progressive glioblastomas are common among younger patients and arise through progression from lower-grade astrocytomas. CDKN2A deletions, PTEN alterations, and EGFR amplification are more prevalent among de novo glioblastomas, whereas p53 mutations are more common among progressive glioblastomas. Loss of heterozygosity (LOH) for chromosome 10 is seen uniformly among both de novo and progressive high-grade astrocytomas. The inactivation of the PTEN gene is found in approximately 30% to 40% of astrocytomas with chromosome 10 loss, and LOH pattern in the remaining astrocytomas strongly supports the presence of another yet unidentified tumor suppressor gene telomeric to PTEN. More than 80% of oligodendrogliomas exhibit LOH for 1 p and 19q alleles. Oligoastrocytomas with 1p/19q LOH are related to oligodendrogliomas, and those with p53 mutations are related to astrocytomas.     

Temporal evolution of perfusion parameters in brain metastases treated with stereotactic radiosurgery: comparison of intravoxel incoherent motion and dynamic contrast enhanced MRI

Although 1p19q codeleted gliomas are the most favorable molecular subgroup of lower-grade gliomas, there are cases with early recurrence or short survival. The objective of this study was to elucidate molecular–genetic and clinicopathological prognostic factors in patients with gliomas showing total 1p19q loss. The study included 57 consecutive patients with codeleted gliomas who were operated at Keio University Hospital between 1990 and 2010. These patients were assessed for chromosomal copy number aberrations, promoter methylation status of the O6-methylguanine-DNA methyltransferase gene (MGMT), and demographic and clinicopathological prognostic factors in diffuse gliomas. No significant difference was observed in the overall survival (OS) of the patients with respect to age (≥40 years vs. <40 years), degree of resection, maximum tumor diameter (≥5 cm vs. <5 cm), histological subtype, and MGMT promoter methylation status. Gain of chromosome 19p and grade III histology were associated with shorter OS (P?=?0.019, 0.061, respectively). Gain of 19p and histological grade III might be negative prognostic factors for the patients with gliomas showing total 1p19q loss. Further investigation is warranted to confirm these notions.     

Bevacizumab in metastatic breast cancer: a meta-analysis of randomized controlled trials

Amplification of the HER2 gene, present in 15–30% of breast carcinomas, correlates with poor outcome and is an indication for treatment with trastuzumab. Standard testing methods for HER2 amplification are fluorescence (FISH) or chromogenic in situ hybridization (CISH). In FISH/CISH scoring, correction for chromosome 17 polysomy is believed to be critical for determination of true HER2 amplification as opposed to increased chromosome 17 copy number. The term “polysomy 17” is widely used and defined as ≥3 copies of the chromosome 17 centromere (probe CEP17, D17Z1). Thus, the centromere is assumed to be representative for the entire chromosome. This study aimed to investigate the frequency of polysomy 17 and its association with HER2 amplification in 111 invasive breast cancer patients by CEP17 CISH and by copy number analysis of a set of 17 genes along chromosome 17 using multiplex ligation-dependent probe amplification (MLPA). Chromosome 17 usually showed a complex pattern of gains and losses by MLPA, unrelated to the copy number status of the centromere. Increase in centromere 17 copy number (denoted “polysomy 17”), as assessed by CEP17 CISH, was found in 19% of the patients. Of these patients, 60% also showed amplification of HER2 measured by MLPA. However, none of the 111 patients showed a true polysomy of chromosome 17 by MLPA. Only two patients (1.8%) had a possible gain of 17q. Amplification of 17p was not found in any of the patients, although a possible loss of 17p was found in one patient. In conclusion, this extensive analysis of amplicons along chromosome 17 shows that true polysomy of chromosome 17, either of the whole chromosome or of the short or the long arm, is very rare in invasive breast cancer. Abnormal CEP17 copy numbers may therefore actually stem from high level gains or amplification of CEP17 regardless of copy number gains of the short and long arms of chromosome 17 and, at least in some cases, correction with CEP17 probes may provide misleading HER2 gene status assessment results.     

Tinzaparin prophylaxis against venous thromboembolic complications in brain tumor patients

Not all Glioblastoma multiforme (GBM, grade IV WHO) manifest the same clinical course. Different prognostic classes may arise from different morphologic and genetic profiles. The observation of oligodendroglial foci within GBM samples and their correlation with genetic alterations may predict a better prognosis. 450 patients affected by histologically proven supratentorial cerebral GBM were treated at our institutions from January 2000 to December 2006: all patients received at least subtotal surgical removal, followed by the same standard radio-chemotherapy adjuvant treatment. In a subgroup of 36 patients (8.0%) an oligodendroglial component was observed. Molecular assessment of these cases was performed and LOH for 1p, 19q and 10q, EGFR amplification and TP53 gene expression was determined. Median age of this subgroup was 52.1 years (range: 29–78 years) vs 62.4 years in the entire GBM population. Chromosome analysis resulted as follows: LOH 1p and/or 19q in 27 cases (75.0%), LOH of 10q in 21 cases (58.1%), EGFR amplification in 14 cases (39%) and TP53 mutation in eight patients (22.2%). OS was of 20.9 months while it was 13.6 months in the entire GBM population. Progression free survival (PFS) was 10.3 months and 7.6 months the entire group. Two-year survival was of 55%. The presence of an oligodendroglial component in GBM appears to be an important prognostic factor to which better prognosis can be related. LOH 1p and 19q was significantly associated with GBM with oligodendroglial component.