P11.21.B Distinct age-related molecular and clinical features inIDH-Wildtype Glioblastoma

Background

The incidence of IDH-wildtype Glioblastomas (IDH-wt GBM) are highest amongst the elderly. However, IDH-wt GBM can occur in younger patients, subsequently associated with a relatively better prognosis. We aimed for comprehensive molecular characterization of IDH-wt GBM in a cohort with large range of Age at onset (AAO) to investigate age-related molecular patterns with potential impact on clinical tumor features and patients′ outcome.

Material and Methods

We performed Whole Exome Sequencing (WES) on 55 patients with IDH-wt GBM. Sanger Sequencing was utilized for the TERT-promotor region as well as selected candidate genes to validate the results of the WES. Moreover, Progression-free- and Overall survival (PFS, OS) data, clinical- and tumor features were collected.

Results

The patients’ median AAO was 58 yrs. (range: 22.9-70.8 yrs.). We divided our study cohort into three subgroups based on AAO quartiles for further analysis: Group A: 22.9-40.4 yrs. (Q1), Group B: 44.5-71.0 yrs. (Q2-3) and Group C: 72.7-79.8 yrs. (Q4). The median OS for all patients was 15.9 months with a PFS of 9.5 months. The median tumor volume at initial presentation was 43.8 cm3 and correlated with AAO: 63.6 cm3 (Group A) vs. 41.2 cm3 (Group C).We identified a median of 32 mutations per tumor. Exome and Sanger sequencing detected frequent alterations on TERT-promoter (76.4%) and EGFR (90.9% gain, 50.1% amplification, 29.1% mutation). Chromosome 7 gain (92.7%) and Chromosome 10 deletion (85.5%) occurred significantly less in younger patients (Group A vs. Groups B/C; p=0.037, p=0.013). However, other individual alterations did not correlate with AAO. Via clustering of various alterations (e.g. TP53, PDGFRA, ATRX), we found an association between a proneural GBM signature and younger AAO (p=0.036). AAO itself had an independent impact on OS: 21.5 Mo. (Group A) vs. 10.1 Mo. (Group C). Moreover, we described TET1-deletions on Chr. 10 in 90.1% of cases, which was not previously described in IDH-wt GBM. Bi-allelic TET1 deletions (32.7%) with concurrent EGFR-amplification had a significant impact on patient’s outcome (OS 12.2 Mo. vs. 17.6 Mo.; p=0.013).

Conclusion

Although GBM signatures showed subtle association with AAO, our data provides no evidence for an age-specific molecular pattern. The vast amount of detected alterations regardless of AAO underlines the overall heterogeneity of IDH-wt GBM. The cause of better prognosis at younger age remains unclear on a molecular explanatory approach. Finally, a bi-allelic deletion of TET1 may represent a relevant alteration in IDH-wt GBM.

OS06.5.A Investigating safety and efficacy of TTFields prior and concomitant to radiotherapy in newly diagnosed glioblastoma - the PriCoTTF phase I/II trial

Background

The EF-14 phase III trial demonstrated improved survival for patients with newly diagnosed glioblastoma (nGBM) when TTFields therapy was added to adjuvant temozolomide chemotherapy. TTFields at 200 kHz are applied to the tumor utilizing arrays on the patients’ scalp. In preclinical studies, a synergistic inhibiting effect on glioblastoma cell proliferation was found for the combination of TTFields and radiotherapy. Based on these findings, we conduct the phase I/II PriCoTTF trial in adult nGBM patients to investigate the safety and efficacy of TTFields therapy initiated prior and concomitant to radiochemotherapy.

Material and Methods

Per study protocol, TTFields therapy is initiated following surgery and completed wound healing. Continuing throughout radiochemotherapy and adjuvant chemotherapy, TTFields therapy is used for approximately 9 months in total with TTFields rechallenge allowed at recurrence. Radiotherapy is conducted with arrays applied on the patients’ scalp. A total recruitment of 33 patients was sought, with 20 patients in arm A receiving normo-fractionated radiotherapy, and 13 elderly patients in arm B receiving hypo-fractionated radiotherapy. Safety and tolerance are the study’s primary endpoint, analyzed by a selection of pre-specified treatment-limiting toxicities (TLTs).

Results

A total of 33 patients have been enrolled. Patients' characteristics were mostly typical for glioblastoma, except for a rather low fraction of patients with gross total resection (GTR, 22.5%). The distribution of adverse events of common toxicity criteria (CTC) grade 3 or higher was comparable to that of established glioblastoma trials. Notably, skin toxicity of CTC grade 3 or higher was quite uncommon (n=2, 6%). As no patient developed TLTs, the study's primary endpoint was met. Median TTFields treatment duration was 8.4 months. Overall survival data was not mature enough (event rate 48%) to allow for a definite conclusion. Notably, on multivariable Cox regression, the number of days with TTFields adherence of more than 23 hours was independently associated with overall survival (HR 0.96, 95% confidence interval 0.93 - 0.99, p=0.008).

Conclusion

The PriCoTTF trial met its primary endpoint indicating that combined TTFields and radiotherapy is safe and well tolerated. High-grade skin toxicity was quite uncommon and the patients with high TTFields adherence seem to perform particularly well. An extended follow-up is required to provide first estimates regarding putative efficacy. At that point in time, the reduced overall TTFields duration and fraction of patients with GTR need to be factored in.

P14.64 PriCoTTF Trial: A phase I/II trial of TTFields prior and concomitant to radiotherapy in newly diagnosed glioblastoma

BACKGROUND

TTFields therapy is applied at 200 kHz by arrays that are placed at the patients’ scalp. In the phase 3 EF-14 trial, survival rates were significantly improved when adding tumor-treating fields (TTFields) to adjuvant temozolomide-based chemotherapy in patients with newly diagnosed glioblastoma (nGBM). In preclinical studies, the combination of TTFields and radiotherapy synergistically impaired proliferation and growth of glioblastoma cells. Here, we present the PriCoTTF trial, which is enrolling nGBM patients and will assess the safety and efficacy of TTFields initiated prior and concomitant to radiochemotherapy.

MATERIAL AND METHODS

Following surgery and complete wound-healing, TTFields therapy is initiated in adult nGBM patients. TTFields therapy continues throughout radiochemotherapy and adjuvant chemotherapy for a total of approximately 9 months. During radiotherapy, the arrays - through which TTFields is delivered - remain on the patients’ scalp. Totally, thirty-three patients are planned to be enrolled in two treatment arms. In arm A, 20 patients receive normo-fractionated radiotherapy, whereas in the elderly arm, arm B, 13 patients receive hypo-fractionated radiotherapy. Concomitant and adjuvant chemotherapy follow institutional standards and interdisciplinary tumor conference recommendations.

RESULTS

The primary endpoint of this trial is safety and tolerance that will be gauged by a set of pre-specified treatment-limiting toxicities. Secondary endpoints include the frequency of adverse events, progression-free survival (PFS), and overall survival (OS). The trial is currently enrolling patients at four sites in Germany. At the time of abstract submission, 9 patients enrolled in Arm B. Patient recruitment for arm A has been completed with 20 patients enrolled. We will present initial practical experiences as well as preliminary safety and tolerance data.

CONCLUSION

There is a biological rationale for combining TTFields and radiotherapy to further improve survival of GBM patients. In the presented phase I/II trial, the safety and efficacy of TTFields initiated prior and concomitant to RT in nGBM will be assessed. In addition, initial efficacy data (phase II) may serve as a rationale for a putative randomized phase III trial.

The prognostic value of IDH mutations and MGMT promoter status in secondary high-grade gliomas

Reports about the prognostic value of IDH mutations and the promoter region of the O6-Methyl-guanyl-methyl-transferase gene in secondary high-grade gliomas (sHGG) are few in number. We investigated the prognostic value of IDH mutations and methylation of the promoter region of the MGMT gene in 99 patients with sHGG and analyzed the clinical course of those tumors. Patients with sHGG were screened for IDH mutations by direct sequencing, and, for promoter status of MGMT gene, by the methylation-specific polymerase chain reaction. A total of 48 of 99 patients (48.5 %) had secondary anaplastic gliomas (Group 1), while 51 patients had secondary glioblastomas (Group 2). The median survival time after malignant progression of all patients with sHGG and with an IDH mutation was 4 years, which is significantly longer than in patients with wild-type IDH (1.2 years, p = 0.009). Patients' survival was not significantly influenced by the tumors' MGMT promoter status, both in Group 1- 9.7 years vs. 6.1 years, methylated vs. unmethylated promoter (p = 0.330)-as well as in Group 2-1.5 years vs. 1.6 years, methylated versus unmethylated promoter (p = 0.829). In our population, the IDH mutation status was not associated with increased PFS or median survival time in sGBM patients. However, patients with secondary anaplastic glioma and IDH mutation had a significantly improved outcome. In addition, IDH mutations are a more powerful prognostic marker concerning both PFS and MS than the MGMT promoter status in those patients.

Complementary therapy use in patients with glioma: an observational study

OBJECTIVE

Despite novel multimodal therapeutic approaches, the vast majority of glial tumors are not curable. Patients may search for complementary therapies in order to contribute to the fight against their disease or to relieve symptoms induced by their brain tumor. The extent of the use of complementary or alternative therapies, the patients' rationale behind it, and the cost of complementary therapy for gliomas are not known. We used a questionnaire and the database of the German Glioma Network to evaluate these questions.

METHODS

A total of 621 questionnaires were available for evaluation from patients with glial tumors of WHO grades II to grade IV. The patients were recruited from 6 neuro-oncologic centers in Germany. Complementary therapy was defined as methods or compounds not used in routine clinical practice and not scientifically evaluated.

RESULTS

Forty percent of the responding patients reported the use of complementary therapies. Significant differences between the group of complementary therapy users and nonusers were seen with respect to age (younger > older), gender (female > male), and education (high education level > low education level). The motivation for complementary therapy use was not driven by unsatisfactory clinical care by the neuro-oncologists, but by the wish to add something beneficial to the standard of care.

CONCLUSIONS

In clinical practice, patients' use of complementary therapies may be largely overseen and underestimated. The major motivation is not distrust in conventional therapies. Neuro-oncologists should be aware of this phenomenon and encourage an open but critical dialogue with their patients.

Multicenter study on prognostic factors in 692 patients with brain metastases of malignant melanoma

9081

Background: This multicenter study aimed to identify prognostic factors in patients with brain metastases from malignant melanoma (BM-MM). Methods: In a retrospective survey in nine cancer centres of the German Cancer Society 692 patients were identified with BM-MM during the period 1986–2007. Overall survival was analysed using Kaplan-Meier estimator and compared by log-rank analysis. Cox proportional hazards models were used to identify prognostic factors significant for survival. Results: The median overall survival of the entire cohort was 5.0 months (95%CI: 4–5). Prognostic factors in the univariate Kaplan- Meier analysis were: Karnofsky Performance Status (≥ 70 vs. <70; p<0.001), number of BM-MM (single vs. multiple; p<0.001), pre-treatment levels of serum LDH (normal vs. elevated; p<0.001), pre-treatment levels of S100 (normal vs. elevated; p<0.001), Prognostic groups according to Radiation Therapy Oncology Group (Class I vs. Class II vs. Class III; p=0.0485), kind of applied treatment (for the cohort with single BM-MM, only) (stereotactic radiotherapy or neurosurgical metastasectomy vs. others; p=0.036). Cox proportional hazards models revealed pre-treatment elevated level of serum LDH (HR: 1.6, 95%CI: 1.3–2.0; p=0.00013) and number of BM-MM (HR: 1.6, 95%CI: 1.3–2.0; p=0.00011) in the whole cohort of patients as independent prognostic variables, whereas in patients with single BM-MM the kind of applied treatment (stereotactic radiotherapy or neurosurgical metastasectomy vs. others; HR: 1.5, 95%CI: 1.1–1.9; p=0.0061) was identified as unique prognostic factor. Conclusions: Overall survival of patients with BM-MM mainly depends on the number of metastases and pre-treatment levels of LDH. In case of a single brain metastasis the application of stereotactic radiotherapy or neurosurgical metastasectomy is by far the most important factor for improving survival.

No significant financial relationships to disclose.

[Analysis of tissue inhibitor of metalloproteinase-2 gene polymorphisms in a caucasian population with abdominal aortic aneurysms]

BACKGROUND

The formation of sporadic abdominal aortic aneurysm (AAA) is explained by a remodelling of the extracellular matrix (ECM) and breakdown of structural components of the vascular wall. Matrix metalloproteinases are the principle matrix-degrading proteases and are known to play a major role in the remodelling of the extracellular matrix in arterial vessels. Their activity is controlled by tissue inhibitors of metalloproteinases (TIMPs). Decreased TIMP-1 and TIMP-2 expression in the extracellular matrix of the walls of AAAs has been demonstrated in several studies. This case-control study was designed to investigate the possible impact of genetic variants of the TIMP-2 gene in the aetiology of AAA and to reproduce a recently described significant difference in allele frequency of the SNP 303G>A in a German population.

METHODS

TIMP-2 single nucleotide polymorphisms (SNPs) were analysed in a study sample of 50 patients with AAA and 41 controls. Differences in genotype and allele frequencies of the identified polymorphisms were determined after sequencing the entire coding region and selected parts of the promoter using the automated laser fluorescence technique.

RESULTS

Six polymorphisms were identified, one of which is described for the first time, located in the intron, (231+23C>T). An association of the SNP 303G>A with the phenotype was not confirmed in our study (p=0.648). However, the CT genotype of the SNP -479C>T was more frequent in patients with AAA than in the control group (p=0.054).

CONCLUSIONS

In our analysis of the TIMP-2 gene, we identified one new SNP. A previously published association of the SNP 303G>A with the phenotype could not be validated in our population. However, we detected an association for the CT genotype of one polymorphism in the promoter region (g-479C>T) and AAA. This result has to be proved in a second study sample.

A MDR1 (ABCB1) gene single nucleotide polymorphism predicts outcome of temozolomide treatment in glioblastoma patients

BACKGROUND

Some patients with glioblastoma multiform do not respond to temozolomide even though they have aberrant promoter methylation of the DNA repair enzyme O(6)-methylguanine methyltransferase (MGMT). This suggests that additional factors hamper temozolomide cytotoxicity. We aimed to confirm first that temozolomide is a target for the multidrug resistance transporter MDR1/ABCB1 and second to investigate whether genetic variants of the MDR1 gene are associated with the survival of glioblastoma patients treated with temozolomide.

MATERIALS AND METHODS

Temozolomide-mediated cytotoxicity was determined by the colorimetric methyl-thiazol-tetrazolium assay in MDR-expressing and MDR-nonexpressing cell lines. Genotypes of three single nucleotide polymorphisms (SNPs) of the MDR1 gene (C1236T, G2677T, and C3435T), MDR1 mRNA expression levels, and the MGMT promoter methylation status were analyzed in 112 glioblastoma patients who had been treated either by surgery plus radiotherapy alone or by additional temozolomide chemotherapy.

RESULTS

In vitro analysis revealed that temozolomide-mediated cytotoxicity is dependent on MDR1 expression. Multivariate analysis of MDR1 genotypes showed that the C/C variant of the exon12 C1236T SNP is predictive for survival of patients treated with temozolomide. This effect was independent of the MGMT methylation status. Patients with the C/C genotype had a 2-year overall survival of 37% compared with 8% and 10% for patients with C/T and T/T genotypes, respectively (P=0.02). No influence was seen in the group of patients with radiotherapy only.

CONCLUSION

The genotype of the MDR1 exon12 C1236T SNP is a novel independent predictive factor for outcome of temozolomide treatment in glioblastoma patients.

Matrix metalloproteinase 2 polymorphisms in a caucasian population with abdominal aortic aneurysm

BACKGROUND

The formation of sporadic abdominal aortic aneurysm (AAA) is explained by remodeling of the extracellular matrix (ECM) and breakdown of structural components of the vascular wall. Matrix metalloproteinase 2 (MMP2) is one of the principal matrix-degrading proteases and is known to play a major role in the remodeling of the extracellular matrix in arterial vessels. Increased MMP2 expression in the extracellular matrix of the walls of AAAs has been shown in several studies. To investigate the possible impact of genetic variants of the MMP2 gene in the etiology of AAA, we conducted this case-control study.

PATIENTS AND METHODS

We analyzed MMP2 single-nucleotide polymorphisms (SNPs) in 51 patients with AAA and 48 controls. Differences in genotype and allele frequencies of identified polymorphisms were determined after sequencing the entire coding region and three selected parts of the promoter.

RESULTS

Eighteen polymorphisms were identified, 6 of which are newly described, with 3 located in the introns (c.IVS1+31C>G, c.IVS7-18G>A, c.IVS10+26C>T) and 3 located in the coding region (c.124G>A, c.1368C>T, c.1860C>T). There were no statistically significant differences in genotype or allele frequencies between the two groups.

CONCLUSIONS

Our analysis of the entire coding region and three parts of the promoter of the MMP2 gene failed to show an association between genetic polymorphisms and AAA, suggesting that variations in the MMP2 gene do not contribute to the development of AAA.

Epigenetic inactivation of SLIT3 and SLIT1 genes in human cancers

In Drosophila, the Slit gene product, a secreted glycoprotein, acts as a midline repellent to guide axonal development during embryogenesis. Three human Slit gene orthologues have been characterised and recently we reported frequent promoter region hypermethylation and transcriptional silencing of SLIT2 in lung, breast, colorectal and glioma cell lines and primary tumours. Furthermore, re-expression of SLIT2 inhibited the growth of cancer cell lines so that SLIT2 appears to function as a novel tumour suppressor gene (TSG). We analysed the expression of SLIT3 (5q35–34) and SLIT1 (1q23.3–q24) genes in 20 normal human tissues. Similar to SLIT2 expression profile, SLIT3 is expressed strongly in many tissues, while SLIT1 expression is neuronal specific. We analysed the 5′ CpG island of SLIT3 and SLIT1 genes in tumour cell lines and primary tumours for hypermethylation. SLIT3 was found to be methylated in 12 out of 29 (41%) of breast, one out of 15 (6.7%) lung, two out of six (33%) colorectal and in two out of (29%) glioma tumour cell lines. In tumour cell lines, silenced SLIT3 associated with hypermethylation and was re-expressed after treatment with 5-aza-2′-deoxycytidine. In primary tumours, SLIT3 was methylated in 16% of primary breast tumours, 35% of gliomas and 38% of colorectal tumours. Direct sequencing of bisulphite-modified DNA from methylated tumour cell lines and primary tumours demonstrated that majority of the CpG sites analysed were heavily methylated. Thus, both SLIT2 and SLIT3 are frequently methylated in gliomas and colorectal cancers, but the frequency of SLIT3 methylation in lung and breast cancer is significantly less than that for SLIT2. We also demonstrated SLIT1 promoter region hypermethylation in glioma tumour lines (five out of six; 83%), the methylation frequency in glioma tumours was much lower (two out of 20; 10%). Hence, evidence is accumulating for the involvement of members of the guidance cues molecules and their receptors in tumour development.

Genesis of cerebral aneurysms--an update

To elucidate the molecular pathogenesis of diseases has become a crucial step in the development of new treatment strategies. Although the pathogenesis of cerebral aneurysms has been studied intensively, it is poorly understood. Endogenous factors like elevated arterial blood pressure, the special anatomy of the Circle of Willis or the effect of haemodynamic factors, particularly originating at vessel bifurcation, are all known to be involved in the growth and rupture of an aneurysm. There is an ongoing discussion as to whether these factors also contribute to the very early steps of pathogenesis. Arteriosclerosis and secondary inflammatory reactions are thought to be elementary preconditions. Exogenous factors like cigarette smoking, heavy alcohol consumption or certain medications known to help generate arteriosclerosis and elevated blood pressure have also been found to be related to the occurrence of cerebral aneurysms. Furthermore, there has been a long-lasting debate on whether aneurysms might develop as a result of an inborn genetic defect. First-degree relatives of patients with cerebral aneurysms have a higher risk of having an aneurysm. In addition, the elevated prevalence of cerebral aneurysms in patients suffering from various inherited diseases points to a genetic background in the development of an aneurysm. Recent advances in molecular biology provide evidence that genetic variants of different candidate genes are associated with the occurrence of cerebral aneurysms. The aim of this review is to expose the current status of these various hypotheses and their contribution to the pathogenesis of cerebral aneurysms in order to provide a basis for future investigations in this field.

Lack of association between endoglin intron 7 insertion polymorphism and intracranial aneurysms in a white population: evidence of racial/ethnic differences

BACKGROUND AND PURPOSE

Endoglin is a component of the transforming growth factor-beta receptor complex and is predominantly expressed on cell surfaces of endothelial cells. A polymorphism of the endoglin gene has previously been found to be associated with the occurrence of intracranial aneurysms in a Japanese population. In our study, we investigated whether this polymorphism is associated with the development of cerebral aneurysm in a white population.

METHODS

The study population consisted of 121 white patients who had been treated for intracranial aneurysms, 124 healthy white blood donors, and 15 Japanese volunteers. Exon 7 of the endoglin gene and adjacent intronic sequences were amplified by polymerase chain reaction and analyzed by using an automated laser fluorescence detection system.

RESULTS

A well-known insertion polymorphism (5'-TCCCCC-3', starting 23 bp distal from the 3' end of exon 7) was identified. The allele frequencies of the polymorphism were 35 (14.5%) of 242 alleles in the aneurysm group and 35 (14.1%) of 248 alleles in the white control group, which does not represent a statistically significant difference (P>0.85). The sequence of the polymorphism is complementary to that reported in the previously mentioned Japanese study. However, the 2 polymorphisms are identical. Under this assumption, the allele frequencies differ significantly among the Japanese controls in that particular study and the white controls in our study (27.8% versus 14.1%, respectively; P=0.0003).

CONCLUSIONS

The genetic polymorphism in the vicinity of 3' end of exon 7 in the endoglin gene was not significantly associated with the occurrence of intracranial aneurysms in the white population. There are ethnic-related differences of allele frequencies between our white controls and the previously reported Japanese controls.

Identification of uncommon chromosomal aberrations in the neuroglioma cell line H4 by spectral karyotyping

To elucidate the reasons why mRNA expression of the LGI1 candidate tumor-suppressor gene was severely reduced in the glioma-derived cell line H4, as demonstrated in a previous study, we performed a cytogenetic analysis of this cell line using conventional methods and fluorescence in situ hybridization (FISH) techniques [spectral karyotyping (SKY), interphase- and chromosome FISH of metaphases (I- and C-FISH)]. Cell line H4 is monoclonal and near triploid (+/-3n). SKY enabled us to detect 24 structural aberrations: unbalanced translocations, n = 12; deletions, n = 10; insertion, n = 1; duplication, n = 1. The results were confirmed by I- and C-FISH analysis using chromosome-specific paints, centromer-specific probes and locus-specific probes for p53, PTEN/MMAC1, LGI1, Cyclin D1, EGR1, ETV6/TEL, AML1, and the genomic region 13q14.3 containing the Rb locus. We found loss of one copy of p53 as well as of one copy of Rb. Complete loss of PTEN/MMAC1 was detected, while all copies of LGI1 and Cyclin D1 were preserved. Interestingly, there was a gain of ETV6/TEL and EGR1, which were each present in quadruplicate. Additionally, the AML1 locus revealed mosaicism of cells with three and four copies, respectively. Additionally, a 5q-chromosome [del(5)(q13q33)] was found, which is one of the common features in hematological malignancies, and der(12)t(1;12) was found, suggesting that there might be an additional ETV6/TEL fusion protein. The combination of SKY, I- and C-FISH demonstrates that the neuroglioma cell line H4 harbors cytogenetic aberrations that are reported to occur in glioma-derived cell lines and additional chromosomal aberrations that have so far not been reported to occur in these cell lines. The complex aberrant karyotype and possibly generation of transcription factors by fusion proteins might be reasons for the impaired mRNA expression of the LGI1 candidate tumor-suppressor gene in cell line H4.

Molecular genetic alterations in glioblastomas with oligodendroglial component

Glioblastoma multiforme is the most malignant astrocytic glioma and usually resistant to chemotherapy. A small fraction of glioblastomas may contain areas with histological features of oligodendroglial differentiation. To determine the molecular genetic alterations in such "glioblastomas with oligodendroglial component", we investigated 13 of these tumors for genetic alterations and/or expression of the TP53, CDKN2A, PTEN, and EGFR genes. In addition, we performed microsatellite analyses for loss of heterozygosity (LOH) on chromosome arms 1p, 19q and 10q. None of tumors showed evidence for LOH on 10q. LOH on 1p was detected in 3 tumors, 1 of which additionally showed LOH on 19q. The 3 tumors with LOH on 1p showed neither TP53 mutations nor nuclear p53 accumulation. In contrast, 9 of 10 tumors without demonstrated losses on 1p showed nuclear p53 accumulation. TP53 mutations were identified in 3 of these cases. Further aberrations detected were epidermal growth factor receptor (EGFR) overexpression (3 of 13 tumors), homozygous CDKN2A deletion (2 of 11 tumors), and PTEN mutation (1 of 13 tumors). Taken together, our results indicate that "glioblastomas with oligodendroglial component" carry heterogeneous genetic alterations. LOH on 10q, PTEN mutation, and homozygous CDKN2A deletion appear to be less common in these tumors as compared to ordinary glioblastomas. Furthermore, a subset of these tumors demonstrates LOH on 1p, i.e., an alteration that has recently been linked to chemosensitivity and good prognosis in anaplastic oligodendrogliomas.

Molecular analysis of the PTEN, TP53 and CDKN2A tumor suppressor genes in long-term survivors of glioblastoma multiforme

Despite multimodal therapy, glioblastoma multiforme (GBM) is associated with a poor prognosis with a median survival of less than 1 year. However, a small number of patients with GBM shows survival times of several years. Although clinical features like age and performance status at diagnosis are well known prognostic parameters, molecular markers for prognosis of overall survival are still lacking. Therefore, we compared 2 age- and gender-matched groups of GBM patients with different post-operative time to tumor progression (TTP), defined as 'short-term' for TTP of less than 6 months (n = 21), and 'long-term' for TTP of more than 24 months (n = 21) for genetic alterations of the PTEN, CDKN2A and TP53 genes as well as overexpression of the EGFR, p53 and Mdm2 proteins. For the GBMs with 'short-term' TTP vs. 'long-term' TTP, the studies revealed PTEN mutations in 4/21 vs. 2/21, TP53 mutations in 5/21 vs. 8/21, homozygous deletion of the CDKN2A gene in 5/21 vs. 6/21, overexpression of EGFR in 7/20 vs. 10/20, accumulation of p53 protein in 9/20 vs. 7/20 and of Mdm2 protein in 0/20 vs. 1/20 cases studied. Taken together, our data indicate that mutations of the PTEN and TP53 tumor suppressor genes, homozygous deletion of the CDKN2A gene as well as overexpression of the EGFR, p53 and Mdm2 proteins lack prognostic significance for overall survival time in patients with GBMs.

An easy and safe method to store and disinfect explanted skull bone

In our department extensive decompression craniectomies became the treatment of choice for patients with massive cerebral oedema following either trauma or acute cerebral infarction. The remarkable survival rates of this neurosurgical technique created the problem of adequate vault defect reconstruction. To evaluate the biological safety of using stored autologous skull flaps for this purpose, we compared three different disinfection methods. Skull bone fragments stored at -21 degrees C for different periods of time were artificially contaminated with clinically relevant strains of Serratia marcescens, Enterococcus faecium and Staphylococcus aureus. As potential methods for disinfection we tested immersion in 3% H2O2, boiling in normal saline for 15 and 30 minutes and a special process of steam disinfection at a temperature of 75 degrees C for 20 minutes. We were able to demonstrate that only steam disinfection completely eliminated the bacterial strains tested. Refrigeration plus steam disinfection of autologous skull bone prior to re-implantation seems to offer reliable safety for its use for defect closure. It is available at reasonable cost in many hospitals and does not require a bone bank.

Peri-operative changes of cellular and humoral components of immunity with brain tumour surgery

Nosocomial infections, which are not uncommon in neurosurgical intensive care medicine, may possibly be favoured by an impairment of immunological competence of the patient. In a prospective observational trial, we investigated several parameters of cellular and humoral immunity in 32 patients before and after resection of an intracranial tumour. We quantified the effects of operative procedure, dexamethasone pretreatment, and tumour type. Dexamethasone alone causes an increase of neutrophilic granulocyte count and monocytes, whereas IgG and eosinophilic granulocytes decrease as well as lymphocytes. CD4+ T lymphocytes (T helper cells) and CD8+ T lymphocytes (T cytotoxic/suppressor cells) were more severely affected than B lymphocytes. Dexamethasone and operation in combination act synergistically on T lymphocytes and IgG, while no synergism is obvious in other clinical test parameters. The skin sensitivity reaction was depressed accordingly. With intracerebral tumours (gliomas WHO grades II to IV), levels of T helper cells and eosinophilic granulocytes were lower, and levels of IgM and neutrophilic granulocytes were higher than with benign extracerebral neoplasms. Postoperative nosocomial infections of the lower respiratory tract occurred almost exclusively in patients subject to severe depression of T helper cells.

Prognostic factors for lower respiratory tract infections after brain-tumor surgery

Nosocomial infection of the lower respiratory tract is a frequent and serious complication after major operations. A 32% incidence of lower respiratory tract infections was found after brain-tumor surgery in 289 patients, with a 21% incidence of pneumonia. In 186 of these patients (Group A), five factors were identified which were associated with an increased risk of postoperative lower respiratory tract infection. These were: age, tumor type, cardiac insufficiency, preoperative disturbances of consciousness, and preoperative corticosteroid treatment. Based on these factors, a risk score was developed which correlated well with the incidence of infection in this group of patients. In a second group of patients (Group B), the derived risk score was applied and was found to possess a high degree of validity. As long as patients were intubated postoperatively, their freedom from infection decreased exponentially, with a half-life of 3.5 days.