Loss of prostaglandin D2 synthase: a key molecular event in the transition of a low-grade astrocytoma to an anaplastic astrocytoma.

Reduction in the mRNA and protein expression of lipocalin-like prostaglandin D(2) (PGD(2)) synthase (PGDS), the main arachidonic acid metabolite produced in neurons and glial cells of the central nervous system, is a significant biological event involved in the malignant progression of astrocytomas and is predictive of poor survival. In vitro, the addition of the main PGDS metabolite, PGD(2), to A172 glioblastoma cells devoid of PGDS resulted in antiproliferative activity and cell death. In vitro PGD(2) substitution also enhanced the efficacy of cyclo-oxygenase-2 inhibitors. This finding has exciting implications for early interventional efforts for the grade 2 and 3 astrocytomas.

IQGAP1 and IGFBP2: valuable biomarkers for determining prognosis in glioma patients.

Clinical treatment decisions and the survival outcomes of patients with gliomas are directly impacted by accurate tumor classification. New and more reliable prognostic markers are needed to better identify the variable duration of survival among histologically defined glioma grades. Microarray expression analysis and immunohistochemistry were used to identify biomarkers associated with gliomas with more aggressive biologic behaviors. The protein expression of IQGAP1 and IGFBP2, when used in conjunction with the World Health Organization grading system, readily identified and defined a subgroup of patients with grade III gliomas whose prognosis was poor. In addition, in patients with glioblastoma multiforme, in whom IQGAP1 and IGFBP2 were absent, long-term survival of more than 3 years was observed. The use of these markers confirmed a nonuniform distribution of survival in those with World Health Organization grade III and IV tumors. Thus, IQGAP1 and IGFBP2 immunostaining supplements current histologic grading by offering additional prognostic and predictive information.

Operative steps in management of benign nerve sheath tumors.

Benign peripheral nerve sheath tumors include the neurofibroma, schwannoma, and their plexiform variants. Operative management begins with an assessment of the relative risks associated with surgery compared with observation. The risks of observation include the risk of malignancy, the progression of symptoms, risk of delayed surgery, and ongoing patient suffering. The risks of surgery include anesthetic problems, wound complications, and neurological injury. New neurological deficits have been reported to occur in approximately 10 to 15% of surgically treated cases. In general, surgery is recommended for symptomatic or progressive lesions. Although the surgical approach will vary depending on the location, type, and extent of tumor, adherence to certain principles will facilitate success. Adequate visualization and successful removal will be achieved with detailed anatomical knowledge, an adequate extensile exposure to visualize the proximal and distal tumor extent, circumferential dissection of the tumor, microsurgical dissection under appropriate magnification, and meticulous hemostasis throughout the procedure.

Risk factors and prophylaxis for deep venous thrombosis in neurosurgery.

Acceptance is increasing for pharmacological prophylaxis against deep vein thrombosis (DVT) and pulmonary embolism (PE) for most types of surgery, but its use remains controversial in neurosurgical patients because of the threat of catastrophic hemorrhage. Consequently, mechanical measures such as sequential calf compression and graduated compression stockings are currently the preferred prophylaxis for neurosurgical patients. However, some patients remain at high risk despite these measures and may require prophylaxis with low molecular weight heparins or unfractionated heparin. In neurosurgical patients, known risk factors for DVT or PE include advanced age, malignancy, limb weakness, prolonged surgery, and cranial as opposed to spinal surgery. Using comprehensive neurosurgery databases, the authors identify more specific neurosurgical diagnoses and procedures as risk factors for DVT and PE, and show increases in the frequency of DVT and PE for the wider neurosurgery population and for glioma patients over time. DVT prophylaxis is compared in public and private hospital settings. This chapter contributes to the changing picture of DVT and PE in neurosurgical patients over the last two decades.

The impact of molecular and clinical factors on patient outcome in oligodendroglioma from 20 years' experience at a single centre.

The increased chemosensitivity of oligodendroglial tumours has been associated with loss of heterozygosity (LOH) of the p arm of chromosome 1 and the q arm of chromosome 19 (LOH 1p/19q). Other clinical and molecular factors have also been identified as being prognostic and predictive of treatment outcome. We reviewed 105 patients with oligodendroglioma treated at a single centre over 20 years. Median survival in oligodendroglioma patients with LOH 1p/19q was significantly longer (10.9 vs. 2.0 years). In the anaplastic oligodendroglioma group, univariate analysis demonstrated decreased patient age, presentation with seizures, use of adjuvant chemotherapy and LOH 1p/19q as predictors of improved survival. Multivariate analysis confirmed LOH 1p/19q as a significant predictor of improved survival (hazard ratio, 3.4; p=0.015). Median survival in patients with anaplastic oligodendroglioma with LOH 1p/19q was 15.4 years vs. 1.2 years for those without LOH 1p/19q. This study confirms the utility of LOH 1p/19q as a prognostic marker in oligodendroglioma.

Post-contrast enhancement as a clinical indicator of prognosis in patients with anaplastic astrocytoma.

Diagnosis of an anaplastic astrocytoma (World Health Organization grade III) is associated with a highly variable prognosis. The identification of clinical markers that allow a more careful delineation of this prognostic spectrum is urgently needed. In this study, we analysed 48 patients with a histological diagnosis of anaplastic astrocytoma and found peritumoral post-gadolinium contrast enhancement to be a clear prognostic marker of poor prognosis. Multivariate analysis also confirmed surgery type, Karnofsky Performance Status score (<70) and increasing age as independent adverse predictors of survival. The survival differences observed in the enhancing and non-enhancing lesions in patients diagnosed with anaplastic astrocytoma supports the existence of a broad anaplastic spectrum of disease, with enhancement being a clinical marker of tumour progression along this spectrum.

Presence of alternative lengthening of telomeres mechanism in patients with glioblastoma identifies a less aggressive tumor type with longer survival.

Patients with glioblastoma (GBM) have variable clinical courses, but the factors that underlie this heterogeneity are not understood. To determine whether the presence of the telomerase-independent alternative lengthening of telomeres (ALTs) mechanism is a significant prognostic factor for survival, we performed a retrospective analysis of 573 GBM patients. The presence of ALT was identified in paraffin sections using a combination of immunofluorescence for promyelocytic leukemia body and telomere fluorescence in situ hybridization. Alternative lengthening of telomere was present in 15% of the GBM patients. Patients with ALT had longer survival that was independent of age, surgery, and other treatments. Mutations in isocitrate dehydrogenase (IDH1mut) 1 frequently accompanied ALT, and in the presence of both molecular events, there was significantly longer overall survival. These data suggest that most ALT+ tumors may be less aggressive proneural GBMs, and the better prognosis may relate to the set of genetic changes associated with this tumor subtype. Despite improved overall survival of patients treated with the addition of chemotherapy to radiotherapy and surgery, ALT and chemotherapy independently provided a survival advantage, but these factors were not found to be additive. These results suggest a critical need for developing new therapies to target these specific GBM subtypes.

Variation of O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation in serial samples in glioblastoma.

Methylation of the promoter region of the O ( 6 ) -methylguanine-DNA methyltransferase (MGMT) gene is known to be predictive of response to temozolomide treatment in patients with glioblastoma. Contrastingly, little is known about variation in the methylation status of the MGMT promoter after treatment or across different regions of the same tumor. About 22 samples from 10 patients who had undergone multiple resections of a glioblastoma were examined with promoter sequencing. Of these, 20 were also analyzed using Methylation Specific PCR (MSP). The methylation status of the MGMT promoter was altered in the specimens obtained pre and post treatment in 2 of 9 samples as assessed by MSP and 7 out of 10 patients as assessed by promoter sequencing. In four patients, the MGMT promoter was unmethylated at primary surgery, but displayed some methylation (32, 44, 12, and 4%) on post-treatment sampling. Alteration in MSP status from unmethylated to methylated was also observed in 2 of these 4 patients. In another patient, methylation increased from 40% on initial sampling to 68% on the second sample. The remaining two patients initially demonstrated some degree of methylation (72% and 12%); subsequent sampling showed no methylation of the MGMT promoter. To ensure variable methylation status was not due to intra-tumoral variability, three to four specimens were sampled from different regions of large glioblastomas (n = 7). Promoter sequencing revealed minimal variation in methylation in all but two sites examined. Immunohistochemistry also demonstrated minimal change in MGMT expression across the tumors. This suggests that variation in MGMT promoter methylation can occur within the same tumor after treatment, necessitating caution in clinical decision-making based on this analysis.

The presence of necrosis and/or microvascular proliferation does not influence survival of patients with anaplastic oligodendroglial tumours: review of 98 patients.

Accurate prognosis for patients with anaplastic oligodendroglial gliomas is increasingly difficult to make. Characterisation of these tumours remains challenging, increasing proportions of oligodendroglial diagnoses in gliomas are reported, and no WHO 2000 grade IV exists for them, so that highly anaplastic tumours can only be grouped with glioblastoma (GBM) or with grade III oligodendroglioma, which have differing clinical behaviour. Longer survival times reported for patients with glioblastoma containing an oligodendroglial element (GBMO) suggest that a grade IV for oligodendroglial tumours might exist. In patients with anaplastic gliomas containing an oligodendroglial element, we explored whether microvascular proliferation (MVP) and necrosis were associated with shorter survival, sufficient to create a grade IV. Biopsies for 98 patients with anaplastic oligodendroglioma, anaplastic oligoastrocytoma or tumours with an oligodendroglial and GBM element, discharged 1998-2004, were identified from databases at three allied neurosurgery units. Pathology reports were reviewed for the presence of MVP and necrosis. Anaplastic oligoastrocytoma and GBMO were combined to measure the effect of an astrocytic element on survival. For anaplastic oligodendroglioma patients, median survival time was 24 months, while for anaplastic oligoastrocytoma or GBMO patients, it was 9 months. Age 60 or over (P=0.006) and astrocytic element (P=0.01) were the only independent predictors of survival. Patients 60 and over with an astrocytic element had 4.6 times the risk of death of patients under 60 with anaplastic oligodendroglioma.A grade IV cannot be created using necrosis or MVP since neither feature predicted survival after adjustment for age and an astrocytic element. However age and an astrocytic element were strong predictors of poorer survival in patients with anaplastic oligodendroglial tumours.