Proliferative activity and prognosis of low-grade astrocytomas

[Histomolecular diagnosis of glial and glioneuronal tumours]

While rare compared to extra-cranial neoplasms, glial and glioneuronal tumors are responsible of high morbidity and mortality. In 2016, the World Health Organization introduced histo-molecular ("integrated") diagnostics for central nervous system tumors based on morphology, immunohistochemistry and the presence of key genetic alterations. This combined phenotypic-genotypic classification allows for a more objective diagnostic of brain tumors. The implementation of such a classification in daily practice requires immunohistochemical surrogates to detect common genetic alterations and sometimes expensive and not widely available molecular biology techniques. The first step in brain tumor diagnostics is to inquire about the clinical picture and the imaging findings. When dealing with a glial tumor, the pathologist needs to assess its nature, infiltrative or circumscribed. If the tumor is infiltrative, IDH1/2 genes (prognostic marker) and chromosomes 1p/19q (diagnosis of oligodendroglioma) need to be assessed. If the tumor appears circumscribed, the pathologist should look for a neuronal component associated with the glial component (glioneuronal tumor). A limited immunohistochemistry panel will help distinguish between diffuse glioma (IDH1-R132H, ATRX, p53) and circumscribed glial/glioneuronal tumor (CD34, neuronal markers, BRAF-V600E), and some antibodies may reliably detect genetic alterations (IDH1-R132H, BRAF-V600E and H3-K27M mutations). Chromosomal imbalances (1p/19q codeletion in oligodendroglioma; chromosome 7 gain/chromosome 10 loss and EGFR amplification in glioblastoma) and gene rearrangements (BRAF fusion, FGFR1 fusion) will be identified by molecular biology techniques. The up-coming edition of the WHO classification of the central nervous system tumors will rely more heavily on molecular alterations to accurately diagnose and treat brain tumors.

Mindbomb Homolog-1 Index in the Prognosis of High-Grade Glioma and Its Clinicopathological Correlation

Introduction:

Gliomas are the most common brain tumors in adults originating from the glial cells. Glioblastoma multiforme is the most malignant and frequent among all gliomas. In recent years, the antibody Mindbomb Homolog-1 (MIB-1) has evolved as a measure of the proliferative nature of the glial tumors. This study aims to investigate the MIB-1 index value as an independent prognostic factor in high-grade gliomas and its correlation with outcome and survival.

Materials and Methods:

Mean MIB-1 index was determined in 51 high-grade glioma tissue samples in formalin. Its correlation with outcome by assessing the clinicoradiological parameters and median survival of patients in months were assessed. Survival analysis was studied by using the Kaplan–Meier bivariate analysis and Cox proportional ratio.

Results:

Preoperative Karnofsky Performance Score, WHO-PS, Neurological Performance Scale, and Mini–Mental Status Examination (MMSE) were statistically significant with respect to outcome and survival, whereas tumor factors such as size and perilesional edema were not. In particular, midline-crossing tumors and deep-seated tumors were significantly associated with high MIB-1 index and by correlation with outcome. There were significantly higher number (P < 0.0001) of patients with Grade IV tumors, with an MIB-1 index value above an arbitrary cutoff of 10% compared to Grade III tumors. In addition, median survival period of patients with low MIB-1 index was longer irrespective of tumor grade.

Conclusion:

Significant correlation between high-grade glioma and MIB-1 index suggests MIB-1 index to be a good prognostic tool, with MIB-1 index and midline-crossing variables being independent prognostic parameters.

Ki-67 proliferation index but not mitotic thresholds integrates the molecular prognostic stratification of lower grade gliomas

Despite several molecular signatures for “lower grade diffuse gliomas” (LGG) have been identified, WHO grade still remains a cornerstone of treatment guidelines. Mitotic count bears a crucial role in its definition, although limited by the poor reproducibility of standard Hematoxylin & Eosin (H&E) evaluation. Phospho-histone-H3 (PHH3) and Ki-67 have been proposed as alternative assays of cellular proliferation. Therefore in the present series of 141 LGG, the molecular characterization (namely IDH status, 1p/19q co-deletion and MGMT promoter methylation) was integrated with the tumor “proliferative trait” (conventional H&E or PHH3-guided mitotic count and Ki-67 index) in term of prognosis definition. Exclusively high PHH3 and Ki-67 values were predictor of poor prognosis (log rank test, P = 0.0281 for PHH3 and P = 0.032 for Ki-67), unlike standard mitotic count. Based on Cox proportional hazard regression analyses, among all clinical (age), pathological (PHH3 and Ki-67) and molecular variables (IDH, 1p/19q codeletion and MGMT methylation) with a prognostic relevance at univariate survival analysis, only IDH expression (P = 0.001) and Ki-67 proliferation index (P = 0.027) proved to be independent prognostic factors. In addition, stratifying by IDH expression status, high Ki-67 retained its prognostic relevance uniquely in the IDH negative patient (P = 0.029) doubling their risk of death (hazard ratio = 2.27). Overall, PHH3 immunostaining is the sole reliable method with a prognostic value to highlight mitotic figures in LGG. Ki-67 proliferation index exceeds PHH3 mitotic count as a predictor of patient's prognosis, and should be integrated with molecular markers in a comprehensive grading system for LGG.

Expression and clinical significance of the proliferation marker minichromosome maintenance protein 2 (Mcm2) in diffuse astrocytomas WHO grade II

Background

The WHO classification system for astrocytomas is not considered optimal, mainly because of the subjective assessment of the histopathological features. Few prognostic variables have been found that stratify the risk of clinical progression in patients with grade II astrocytoma. For that reason there is a continuous search for biomarkers that can improve the histopathological diagnosis and prognostication of these tumours.

Aim

This study was designed to investigate the prognostic significance of the proliferative marker Mcm2 (minichromosome maintenance protein 2) in diffuse astrocytomas WHO grade II and correlate the findings with histopathology, mitoses, and Ki67/MIB-1 immunostaining.

Method

61 patients with histologically verified grade II astrocytoma (WHO 2007) were investigated. Paraffin sections were immunostained with anti-Mcm2, and the Mcm2 proliferative index (PI) was determined as the percentage of immunoreactive tumour cell nuclei.

Results

Mcm2 PI was not associated with any histopathological features but correlated significantly with mitotic count and Ki67/MIB-1 PI (p<0.05). In the survival analyses Mcm2 showed trends to poorer survival, however, statistical significance was not achieved in the univariate analyses (p>0.05).

Conclusions

In our hands Mcm2 immunostaining has no advantage over Ki67/MIB-1 in the evaluation of grade II astrocytomas. Larger studies are needed to fully clarify the prognostic role of this biomarker.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1715002791944037

Prognostic significance of sirtuin 2 protein nuclear localization in glioma: an immunohistochemical study

The sirtuin 2 (SIRT2) protein is a member of the sirtuin family and homologous to Sir2 (silent information regulator 2) of Saccharomyces cerevisiae. To assess the pathobiological significance of SIRT2 protein expression and/or subcellular localization in human glioma, we examined SIRT2 protein expression in human gliomas using a polyclonal anti-SIRT2 antibody and immunohistochemistry. In this study, samples from 23 patients with glioblastoma (GB, grade IV), 8 patients with diffuse astrocytoma (DA, grade II) and 5 healthy individuals were examined. We established a SIRT2 labeling index (SIRT2-LI) that represents the percentage of cells with SIRT2 localized to the nucleus. The mean SIRT2-LI was 65.8±18.6 in GB samples, 41.2±22.8 in DA samples, and 28.6±12.3 in normal control samples. The SIRT2-LI of GB samples was significantly higher than that of normal control samples (P<0.01, Mann-Whitney's U-test) and that of DA samples (P<0.05). Moreover, the SIRT2-LI was positively correlated with malignant progression. Specifically, samples from patients with GB were divided into two groups, low SIRT2-LI (<60%) and high SIRT2-LI (≥60%), and the patients with low SIRT2-LI samples survived significantly longer than patients with high SIRT2-LI samples (P<0.05, Kaplan-Meier method and log-rank test). In conclusion, SIRT2-LI was indicative of glioma malignancy, and it may be predictive of GB patient survival.

Long-term follow-up in adult patients with low-grade glioma (WHO II) postoperatively irradiated. Analysis of prognostic factors

AIM

To report the long-term follow-up of a cohort of adult patients with LGG post-operatively irradiated in one institution, and to identify prognostic factors for progression free survival.

BACKGROUND

There is little consensus about the optimal treatment for low-grade glioma (LGG), and the clinical management of LGG is one of the most controversial areas in neurooncology. Radiation therapy is one option for treatment of patients with LGG, whereas other options include postoperative observation.

MATERIALS AND METHODS

Between 1975 and 2005, 180 patients with LGG (WHO II) received postoperative irradiation after non radical (subtotal or partial) excision. Patients had to be 18 years of age or older, and have histologic proof of supratentorial fibrillary (FA), protoplasmic (PA) or gemistocytic astrocytoma (GA). Radiotherapy was given within 3-10 weeks after surgery. Treatment fields were localized and included the preoperative tumor volume, with a 1-2 cm margin, treated to a total dose of 50-60 Gy in 25-30 fractions over 5-6 weeks.

RESULTS

Actuarial ten-year progression free survival (APFS) in the whole group was 19%. The worse prognosis was observed in patients with GA. Ten-year APFS rates for GA, PA and FA were 10%, 18% and 22%, respectively.

CONCLUSION

The findings from our long-term cohort of 180 patients with LGG confirmed by uni- and multivariate analysis demonstrated that only astrocytoma histology significantly determined the prognosis. The best survival was observed in patients with the fibrillary variant, and the worst for the gemistocytic one.

Long-term molecular changes in WHO grade II astrocytomas following radiotherapy

Monitoring the long-term radiotherapy-associated molecular changes in low-grade gliomas (LGGs) facilitates the understanding of LGG response to radiotherapy. In this study, we used immunohistochemistry to analyze the expression of Ki-67, tumor protein P53 (TP53), P21, and P27 in 8 paired WHO grade II astrocytoma samples. The interval between radiotherapy (RT) and the second surgery was more than 3 months in all cases. The average Ki-67 labeling index (LI) was 5.3% in pre-RT samples and 11.54% in post-RT samples. Ki-67 LI was higher in the primary tumors that underwent malignant transformation observed at the second surgery after radiation. Post-RT Ki-67 LI decreased in 2 cases with an interval of less than 12 months between RT and the second surgery. TP53 expression was found in 3 out of 4 pre-RT samples with malignant transformation and in 1 out of 4 pre-RT samples without malignant transformation. Post-RT TP53 increased in 2 cases in which increased expression of P21 or P27 was also observed. Our study suggests that radiotherapy can inhibit WHO grade II astrocytoma proliferation as reflected by Ki-67 LI, but the effect attenuates with time. In addition, there is a tendency of malignant transformation for WHO grade II astrocytomas with a high Ki-67 level or TP53 expression in initial samples.

The expression level of sphingosine-1-phosphate receptor type 1 is related to MIB-1 labeling index and predicts survival of glioblastoma patients

Although there are many reports on the clinical use of the MIB-1 labeling index (LI), which is a measure of proliferative activity in astrocytomas; its significance varies between studies. There are no known molecules that are directly linked to the MIB-1 LI in astrocytomas. We evaluated the clinical value of the MIB-1 LI in our human glioblastoma cases and determined the molecules that possibly influenced the MIB-1 LI. An immunohistochemical study of the MIB-1 protein was performed and MIB-1 LIs of 38 glioblastomas were determined. In the same cases, epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor-alpha (PDGFRA), and sphingosine-1-phosphate receptor type 1 (S1P(1)), which are known regulators of glioma cell proliferation, were detected and quantified by quantitative real-time-PCR or western blotting. Kaplan-Meier survival curves for 38 patients with glioblastomas showed that a high MIB-1 LI correlated with poor survival (P < 0.05). Among the molecules tested, only the low expression of S1P(1) was significantly correlated with the high MIB-1 LI in glioblastomas (P < 0.05). Multivariate analysis revealed that the S1P(1) expression level was a significant prognostic factor. Our results indicate that the MIB-1 LI is an important prognostic factor in human glioblastomas. Furthermore, downregulation of S1P(1) expression increases proliferative activity, and thus enhances the malignancy of glioblastomas, resulting in a poor survival.

Low Grade Gliomas. Can We Predict Tumour Behaviour from Imaging Features?

Low grade gliomas (WHO grade II) are diffuse, infiltrative glial tumours of the brain. The low grade glioma group includes a number of entities, namely diffuse astrocytoma, oligodendroglioma and oligoastrocytoma. This group of the low-grade gliomas share certain common issues of behaviour, clinical assessment and management. Even though these tumours are termed low grade they are not to be considered “benign”: untreated they are invariably fatal. They may remain “stable” for many years and hence a “watch and wait” treatment policy is often adopted. Unfortunately some tumours progress more rapidly than others with dedifferentiation into high grade tumours which become rapidly fatal. Based on standard imaging criteria it has been difficult to predict which of these low grade gliomas will progress more rapidly. Treatment decisions would benefit from some prediction as to which tumours are likely to progress more rapidly than others. This review will discuss some of the imaging features that may help to predict which low grade gliomas will progress more rapidly than others. Such imaging features include the rate of growth on serial imaging; the morphological features that parallel genetic markers; the assessment and change of tumour vascular status as assessed by MR perfusion imaging and tumour characteristics on PET and MR spectroscopy.

Expression of cell cycle inhibitors p21, p27, p14 and p16 in gliomas. Correlation with classic prognostic factors and patients' outcome

Gliomas are among the most aggressive and treatment-refractory of all human tumors. The aim of the present study is to evaluate the role of the expression of cell cycle molecules as prognostic indicators in gliomas. We immunohistochemically analyzed the expression of p21, p27, p14, p16, p53 and proliferation marker Ki67, in 67 low and high grade astrocytic tumors. High grade tumors exhibited higher labeling indices for Ki67 (P = 0.004), p53 (P = 0.039) and slightly higher index for p21 (P = 0.07) compared to low grade tumors. p14 and p16 were more frequently present in low grade tumors (P = 0.001 and P = 0.052, respectively). Worse survival was correlated with high grade tumors (P < 0.0001) and higher Ki67 index (P < 0.0001). Cox regression analysis revealed that only age, grade and marginally Ki67 index were independent prognostic factors. Cell cycle alterations are involved in the malignant progression of astrocytomas, but only age, tumor grade and proliferating index can predict the outcome of the patients with glioma.

Acromegaly and anaplastic astrocytoma: coincidence or pathophysiological relation?

Insulin-like growth factor type I (IGF-I) is an important promoter in the tumorigenesis of several extracranial and intracranial neoplasms. In astrocytic-cell tumors, the role of autocrine and paracrine IGF-I expression in enhancing tumoral progression is well established. However, the influence of systemic IGF-I levels on the clinical behavior of astrocytic neoplasms remains an open subject of research. We report the case of a 28-year-old man who presented simultaneously with acromegaly and an anaplastic astrocytoma, which had rapidly progressed from a low-grade astrocytoma. The coexistence of systemic IGF-I hypersecretion with a quick progression in the histopathological grade of the astrocytoma raises the compelling question of whether the clinical behavior of the astrocytic tumor was influenced by the acromegalic status. The role of IGF-I signaling in the pathogenesis of astrocytic-cell tumors and the experience with therapeutic strategies addressing this pathway in astrocytomas are also discussed.

The clinical value of Ki-67/MIB-1 labeling index in human astrocytomas

The current WHO classification of human astrocytomas has limitations in predicting prognosis and diagnosis, and there is a need for additional factors. Several studies have investigated the clinical value of proliferative activity in these tumors, especially the Ki-67/MIB-1 labeling index (LI). The aim of this study was to review the literature on this topic to get a survey of the current experience. All studies show increasing values of Ki-67/MIB-1 LI with increasing grade of malignancy. Most of them demonstrate that MIB-1 LI differentiates well between diffuse astrocytomas WHO grade II (AII) and anaplastic astrocytomas (AA) and between AII and glioblastomas (GM), but not between AA and GM. There is, however, considerable overlap of indices between the different malignancy groups. Further, in most studies positive correlations between MIB-1 LI and survival are found, though the proposed cut-off values vary substantially between the reports. The studies reviewed report MIB-1 LI as an important prognostic factor in human astrocytomas. Due to the great spread of values between the various tumor grades, however, MIB-1 LI cannot be used as a diagnostic factor alone but should be used in combination with established criteria of histological malignancy. It may be especially useful in cases where histology reveals a low-grade astrocytoma whereas other parameters indicate a more malignant neoplasm. Thus, it is our opinion that MIB-1 LI should be a part of the routine investigation in patients with astrocytic tumors. Until larger multicenter studies based on standardized immunohistopathological procedures have been completed, each laboratory has to establish its own practice.

Prognostic significance of the immunohistochemical index of survivin in glioma: a comparative study with the MIB-1 index

OBJECTIVE

Survivin has been identified as a protein expressed in cancer cells and a member of the inhibitor-of-apoptosis protein family. Recent studies suggest that the expression of survivin increases during the G2/M phase of the cell cycle, and may be used in clinical prognosis. We examined whether survivin expression in human gliomas would be a correlative of prognosis.

METHODS

We prepared polyclonal anti-survivin serum to establish a survivin index for stained sections, using an immunohistochemical procedure, according to the method used for scoring MIB-1 index, and then stained 29 paraffin-embedded sections from surgical specimens of 29 patients who were classified into three grades of World Health Organization with the mean age of low grade astocytoma (grade II) being 34.7; anaplastic astrocytoma (grade III), 48.8; and glioblastoma multiform (grade IV), 58.4.

RESULTS

On staining with the anti-survivin antiserum, all specimens contained positive cells, but the survivin index was heterogeneous among grades. The mean percentage of immunoreactive cells in each specimen was 70.0 (SD 18.2) in grade II, 81.3 (16.5) in grade III, and 85.0 (13.6) in grade IV. Then we compared the survivin index to the MIB-1 index and found that in low-grade gliomas (grade II and III), the difference in survival times between the high and low survivin indexes was significant (P=0.007), whereas that between the high and low MIB-1 indexes was not significant (P=0.092). ONCLUSION: Survivin is more sensitive marker than MIB-1 for the evaluation of low-grade gliomas in that it helps to predict patient survival. Much larger glioma patient series are needed to validate the findings of our limited study.

The Ki-67 labeling index as a prognostic factor in Grade II oligoastrocytomas

OBJECT

This study was conducted to determine whether proliferative tumor activity, as assessed using the Ki-67 immunohistochemical labeling index (LI), has prognostic utility for patients with Grade II oligoastrocytomas.

METHODS

The study period spans the years 1988 to 2000. In a retrospective analysis, the authors selected cases with biopsy-proven diagnoses of Grade II oligoastrocytomas on initial presentation. The authors added new patients to this group and followed all patients prospectively at the University of Virginia Neuro-Oncology Center. Twenty-three adult patients were followed for at least 1 year (median 40.3 months). Eleven patients with Grade II tumors and initial Ki-67 LIs less than 10% had a significantly longer median time to tumor progression (TTP, 51.8 months compared with 9.9 months) and a longer median survival (93.1 months compared with 16.1 months) than 12 patients with initial Ki-67 LIs of 10% or greater. Twelve patients with Grade III oligoastrocytomas had a mean TTP that was similar to the TTP of patients with Grade II tumors and high Ki-67 LIs (mean 4 months compared with 9.9 months) and duration of survival (13.3 months compared with 16.1 months).

CONCLUSIONS

Patients with a Grade II oligoastrocytoma and a Ki-67 LI of 10% or greater have a much shorter TTP and potentially a poorer disease prognosis than expected--more similar to patients with a Grade III oligoastrocytoma. These results indicate that in the future a measure of proliferative activity should be taken into consideration along with the World Health Organization grading criteria for oligoastrocytomas.

Magnetic source imaging supports clinical decision making in glioma patients

OBJECTIVE

This study addresses the potential utility of preoperative functional imaging with magnetoencephalography (MEG) for the selection of glioma patients who are likely to benefit from resective surgical treatment regarding postoperative morbidity.

METHODS

One hundred and nineteen patients with gliomas adjacent to sensorimotor, visual and speech related brain areas were investigated preoperatively with a MAGNES II biomagnetometer. In each patient the pre-surgical evaluation was focussed on the visual, sensorimotor cortex and/or of the speech related brain areas. A grading system was then used according to the distance of the MEG activation sources to the nearest tumour border to determine the further treatment. The therapeutic options consisted in conservative treatment, stereotactic biopsy and/or a radiation and chemotherapy, substantial cytoreduction and the gross total removal of the lesion.

RESULTS

From 119 investigated patients, 55 patients (46.2%) were not considered for surgery due to tumour invasion to functional cortex. Sixty four patients (53.8%) were chosen for resective surgery. In the surgical group only four patients (6.2%) suffered from neurological deterioration.

CONCLUSIONS

Magnetic source imaging (MSI) proved to be a valuable help in the clinical decision making process of lesions adjacent to functional important brain areas. The relative high number of patients in whom MSI warns of the postoperative crippling sequelae may lead to a better selection of patients who benefit from resective surgery. This method may help to find the patients for whom conservative treatment seems to be more favourable concerning quality of life in the surviving time.

Interobserver Reproducibility of MIB-1 Labeling Index in Astrocytic Tumors Using Different Counting Methods

MIB-1 labeling index has been used as a complementary method to differentiate better and worse prognostic groups of astrocytic tumors. However, its reproducibility has been doubted because of the interlaboratory and interobserver variability. We studied the interobserver reproducibility of four manual counting methods of MIB-1 labeling index, including direct counting, area fraction, line intersection with a graticule, and line intersection without a graticule to estimate the total number of the cells. Using line intersection estimate, either with or without a graticule, yielded a worse result. Those MIB-1 labeling indices of astrocytomas were overlapping with those of anaplastic astrocytomas and glioblastomas. Besides, the intraclass correlation coefficient was smaller, and the coefficient of variation was greater than that attained when using a graticule and counting the total number of cells either directly or by area-fraction estimate. The level of interobserver agreement using an MIB-1 labeling index cutoff value of 11.0 was moderate to substantial when applying the line-intersection estimate, and it was almost perfect when applying the direct counting or the area-fraction estimate. The interobserver reproducibility and agreement of MIB-1 labeling index in astrocytic tumors were different depending on the counting methods. Direct counting with a graticule yielded the best result. Before establishing reference standards for staining and counting, the reproducibility of MIB-1 labeling index should be verified.

Supratentorial grade II astrocytoma: biological features and clinical course

Because of its unpredictable clinical course, treatment strategies for low-grade (grade II) astrocytoma vary from "wait and see" to gross tumour resection followed by immediate radiotherapy. Clinical studies on grade II astrocytoma show that 5-year-survival ranges from 27% to 85% of patients with very few consistent prognostic variables besides the patient's age and the presence of neurological deficit. There is no universally recognised choice of therapy for patients with astrocytoma grade II, partly because of the shortcomings of histological classification systems. Routine microscopy tends to underestimate malignancy grading of astrocytomas and in most cases cannot distinguish between indolent and progressive subtypes. Recent studies suggest that proliferation and genetic markers can be used to identify subgroups of astrocytoma grade II with a rapid progressive clinical course. Therefore these markers should be included in ongoing and future clinical studies of patients with astrocytoma grade II.

Ki-67 immunoreactivity, basic fibroblastic growth factor (bFGF) expression, and microvessel density as supplementary prognostic tools in low-grade astrocytomas. An immunohistochemical study with special reference to the reliability of different Ki-67 antibodies

Low-grade diffuse astrocytomas are generally slow-growing tumors; however, they may progress to anaplastic astrocytomas or glioblastomas. As existing grading systems fail to distinguish these tumors, ongoing research strives to identify new prognostic markers. In this study, 22 adult patients with supratentorial diffuse astrocytomas, WHO grade II, were investigated to clarify whether proliferative activity, assessed by different Ki67 antibodies (MIB-1, NC-MM1, NC-Ki67p, rahKi67), expression of basic fibroblast growth factor (bFGF) or microvessel density have prognostic power. The Ki67 antibodies revealed low proliferation indices (PI); however, there was a wide spread of values, ranging from 0.1% to about 10%. In general, a positive correlation between the different Ki67 PIs was found. In 12 of 22 cases, bFGF immunoreactivity was recorded. Microvessel density was generally low. MIB-1 PI was the only prognostic factor of statistical significance. Ki67 PI, obtained by using the monoclonal antibody MIB-1, can thus serve as a prognostic factor capable of identifying subsets of low-grade diffuse astrocytomas with a potentially more aggressive clinical behavior.

Prognostic factors for survival in adult patients with cerebral low-grade glioma

PURPOSE

To identify prognostic factors for survival in adult patients with cerebral low-grade glioma (LGG), to derive a prognostic scoring system, and to validate results using an independent data set.

PATIENTS AND METHODS

European Organization for Research and Treatment of Cancer (EORTC) trial 22844 and EORTC trial 22845 are the largest phase III trials ever carried out in adult patients with LGG. The trials were designed to investigate the dosage and timing of postoperative radiotherapy in LGG. Cox analysis was performed on 322 patients from EORTC trial 22844 (construction set), and the results were validated on 288 patients from trial 22845 (validation set). Patients with pilocytic astrocytomas were excluded from this prognostic factor analysis.

RESULTS

Multivariate analysis on the construction set showed that age > or = 40 years, astrocytoma histology subtype, largest diameter of the tumor > or = 6 cm, tumor crossing the midline, and presence of neurologic deficit before surgery were unfavorable prognostic factors for survival. The total number of unfavorable factors present can be used to determine the prognostic score. Presence of up to two of these factors identifies the low-risk group, whereas a higher score identifies high-risk patients. The validity of the multivariate model and of the scoring system was confirmed in the validation set.

CONCLUSION

In adult patients with LGG, older age, astrocytoma histology, presence of neurologic deficits before surgery, largest tumor diameter, and tumor crossing the midline were important prognostic factors for survival. These factors can be used to identify low-risk and high-risk patients.

Evaluation of molecular markers in low-grade diffuse astrocytomas: loss of p16 and retinoblastoma protein expression is associated with short survival

Diffuse astrocytomas have a median survival of 6-8 years. However, in a minority of cases that are histologically low grade, progression is rapid, leading to death within 2 years. Loss of p16, retinoblastoma protein, and deleted-in-colon-carcinoma protein expression, and monosomy of chromosome 10 have been shown to occur in malignant astrocytic tumors. We have investigated the prognostic value of expression of these markers, using techniques applicable in many histopathology laboratories, in diffuse astrocytomas that are histologically low grade. Paraffin sections from 71 diffuse, supratentorial, low-grade astrocytomas, from patients with at least 8-year survival data, were immunostained with antibodies to p16, deleted-in-colon-carcinoma protein, p53, Ki67, and retinoblastoma protein. In situ hybridization with a digoxigenin-labeled probe to chromosome 10 was used to assess chromosomal loss. In most cases there was immunostaining of virtually all tumor cell nuclei with antibodies to p16 and retinoblastoma protein. Three of the 68 tumors in which assessment of p16 was possible included discrete foci with lack of detectable immunoreactivity in tumor cells. The three patients concerned had a significantly shortened median survival (1.1 years vs 4.4 years in those without loss of p16; p <0.01). In six of the 61 cases where assessment of retinoblastoma protein was possible, <70% of tumor cell nuclei showed immunoreactivity. These six patients had a shorter survival (4.0 years) than had the remaining patients (5.4 years), although this difference was not statistically significant. The tumor from one of these patients included areas where only 36% of tumor cells showed retinoblastoma protein immunoreactivity, and this patient survived only 1.5 years. Tumors showing loss of both p16 and retinoblastoma were not seen. p53 and deleted-in-colon-carcinoma protein expression was highly variable and did not correlate with survival. Tumors with monosomy for chromosome 10 were not identified. Both polyploidy and the Ki67 labeling index were significantly associated with the p53 labeling index but not with survival. Focal loss of p16 or retinoblastoma protein is demonstrable in approximately 5% and 10% of diffuse low-grade diffuse astrocytomas, respectively. Tumors with focal loss of immunoreactivity for these proteins are associated with shorter survival than those without, suggesting that immunohistochemistry for p16 and retinoblastoma protein may be a useful adjunct to other methods for assessing the prognosis of astrocytomas.

Ki-67: a prognostic factor for low-grade glioma?

PURPOSE

Immunohistochemical techniques were used to detect the expression of Ki-67, a nuclear proliferation marker, in 180 low-grade glioma tumor specimens to determine whether Ki-67 is a prognostic predictor of survival or tumor recurrence.

MATERIALS AND METHODS

A clinical database of 180 low-grade glioma patients (35 children aged </=18 years and 145 adults) was compiled. Eighty patients had received postoperative radiotherapy (RT) and 100 patients had had RT deferred until the time of tumor progression/recurrence. Ki-67 indexes were evaluated retrospectively on tumor specimens from these patients using a semiautomated computer analysis technique. Ten observations were averaged per patient. The maximal Ki-67 value was recorded.

RESULTS

The correlation between the Ki-67 index and survival was much higher for the averaged Ki-67 value than for the maximal value. Of the tumor specimens, 29% had a negative Ki-67 index (i.e., zero Ki-67 positive cells) and 7.7% had an average Ki-67 index of >/=5%. An average Ki-67 value of >/=5% was prognostically significant for reduced cause-specific survival (CSS, p = 0.05) and a Ki-67 level >/=10% was strongly significant of a poor survival outcome (p = 0.009). Ki-67 was not prognostically significant for progression-free survival. Other prognostically significant factors for CSS included age (p = 0.05), Karnofsky performance status (p = 0.0001), radiation dose (p = 0.02), extent of surgical resection (biopsy vs. others, p = 0.004), and timing of radiation (p = 0.0005). Ki-67 did not remain an independent statistically significant factor for CSS on multivariate analysis. Age and Ki-67 positivity (both maximal and average values) directly correlated (i.e., advancing age was associated with a higher Ki-67 index). When the patient group was further subdivided by age and timing of RT (postoperative vs. deferred), the prognostic significance of Ki-67 for CSS was lost. Within the deferred RT subgroup, a maximal Ki-67 >2% was associated with a worsened CSS. Within the pediatric population, Ki-67-negative patients had a 5-year CSS and progression-free survival of 100%. The 5-year CSS and progression-free survival declined significantly to 84% and 67% for patients with tumors demonstrating any degree of Ki-67 positivity (p = 0.005 and p = 0.006, respectively).

CONCLUSION

Ki-67 is a useful predictor of CSS in low-grade gliomas; however, it is not independent of other prognostic factors, particularly age. Although Ki-67 was not helpful in predicting which adult patients were likely to benefit from postoperative RT, the results of the present study indicate a possible utility in the selection of pediatric patients for RT and in the selection of poorer prognosis patients for clinical trials.

Ki-67 labeling is correlated with the time to recurrence in primary glioblastomas

The Ki-67 labeling index (LI) was shown in many cut-off studies to be significantly correlated to the postoperative survival probability in gliomas in univariate and multivariate analyses. However, a direct relationship of the Ki-67 LI and the growth fraction, respectively, to clinical growth parameters was not demonstrated in a single tumor type of this group until now. We compared the Ki-67 LI of 20 primary glioblastomas and their recurrent tumors with the time to reoperation for recurrence. Regression analyses showed (1) a high reproducibility of the LIs at the second versus the first operation corresponding to an inherent growth potential of a given individual tumor and (2) a strong inverse correlation of LI to time to recurrence (TR) (r = -0.92). Additionally to a lower LI (corresponding to a smaller growth fraction), a longer cycle time could be derived in slowly growing as compared to rapidly growing tumors. A direct relationship of the Ki-67 LI to a clinical time parameter (the TR) was obtained, and a predictive significance of individual LIs in glioblastomas could be defined.

Interobserver variability associated with the MIB-1 labeling index: high levels suggest limited prognostic usefulness for patients with primary brain tumors

BACKGROUND

The use of the MIB-1 labeling index (LI) as a potential prognostic marker for patients with primary brain tumors is controversial. Many studies advocating its prognostic usefulness have suggested discrete MIB-1 LI cut-off values, above which patients have significantly worse outcomes. However, interobserver variability associated previously with MIB-1 LI calculation has not been reported despite the fact that the degree of interobserver variability impacts the clinical usefulness of such cut-off values.

METHODS

MIB-1 LIs were calculated independently using a standardized protocol by six pathologist observers for 50 astrocytic gliomas of varying grades. The level of interobserver agreement was determined by calculating kappa statistics for pairwise pathologist comparisons using MIB-1 LI cut-off values of 2.5%, 5.0%, 8.0%, 11.0%, and 15.0%. Spearman rank correlation coefficients were used to assess the pairwise associations between observer MIB-1 LIs.

RESULTS

Although there was general agreement among pathologists regarding whether an MIB-1 LI for a given astroglial tumor was low, moderate, or high based on the analysis of correlation, a high level of interobserver variability was associated with the determination of specific MIB-1 LIs. The highest level of agreement occurred using a cut-off value of 5.0%, with pairwise kappa statistics for this value ranging from 0.52 to 0.80.

CONCLUSIONS

The high level of interobserver variability suggests that proposed discrete MIB-1 LI prognostic cut-off values most likely are not useful clinically for predicting outcome for individual patients with primary brain tumors. Further prospective studies are needed investigating the prognostic usefulness of MIB-1 LI ranges that optimize interobserver agreement.

Diagnosis and management of astrocytomas, oligodendrogliomas and mixed gliomas: a review

Low-grade gliomas are a diverse group of neoplasms which, as the name implies, are thought to arise from glial cells. Common among this group are astrocytomas (low-grade astrocytoma; LGA), oligodendrogliomas and mixed gliomas. Among these, LGA is the commonest low-grade glioma and, occasionally, although incorrectly, the terms are used interchangeably. Advances in imaging technology have improved the accuracy of preoperative diagnosis. The management of low-grade gliomas is controversial. Recent evidence suggests that previously considered standard therapy (i.e. surgery plus radiotherapy) may not be in the patient's best interests. A review of the available published research concerning low-grade gliomas is therefore timely.

Tumor angiogenesis of low-grade astrocytomas measured by dynamic susceptibility contrast-enhanced MRI (DSC-MRI) is predictive of local tumor control after radiation therapy

PURPOSE

To assess regional cerebral blood volume (rCBV) as a surrogate marker of angiogenesis in patients with low-grade fibrillary astrocytoma before radiation therapy and to correlate measured values with clinical outcome after fractionated stereotactic radiotherapy (FSRT).

METHODS

Twenty-five patients with histologically proven fibrillary astrocytomas were examined using dynamic susceptibility contrast-enhanced MRI before radiotherapy. Radiotherapy was delivered to mean and median total doses of 60.9 and 60 Gy, respectively (range 55.8-66 Gy). During MRI for treatment planning, 55 T2*-weighted gradient echo images were acquired before, during, and after i.v. contrast-bolus injection. The acquired signal-time curves were converted into concentration-time curves. By normalization to an arterial input function, absolute and relative rCBV values were calculated. Measured pretherapeutic rCBV data were correlated to outcome in terms of local control after FSRT.

RESULTS

Mean pretherapeutic rCBV for astrocytomas was 6.5 +/- 3.7 ml/100 g tissue. Mean and median follow-up times were 47.8 and 52 months, respectively. Fifteen tumors recurred during the period, with a mean and median latency of 39.1 and 42 months, respectively. Tumors recurring earlier than 42 months after FSRT showed a higher pretreatment rCBV than tumors recurring later and tumors in continued local control (8.12 +/- 4.48 ml/100 g vs. 6.0 +/- 2.3 ml/100 g and 4.73 +/- 2.47 ml/100 g; p = 0.02 and p = 0.03). The respective ratios of tumor rCBV in early recurrent tumors to gray matter and white matter rCBV were 0.98 +/- 0.38 and 2.17 +/- 1.36 as compared with 0.79 +/- 0.14 and 1.44 +/- 0.29 in locally controlled tumors (p = 0.074 and p = 0.056).

CONCLUSIONS

In fibrillary low-grade astrocytomas, a noninvasive assessment of angiogenesis as indicated by rCBV measurement was feasible. The present data suggest that high pretherapeutic angiogenic activity in low-grade astrocytomas indicates a subgroup of tumors at higher risk for early local recurrence or malignant transformation after FSRT.

Rehabilitation of persons with central nervous system tumors

A tumor that affects the central nervous system can have a dramatic impact on the individual affected, as well as his or her family and friends. The tumor, regardless of extent or location, may affect the physical, social, vocational, and emotional capabilities of the individual. Basic aspects of rehabilitation for patients with tumors affecting the brain and spinal cord are reviewed in this article. The authors have found that the same principles of neurorehabilitation applied to persons with traumatic brain injury, stroke, and traumatic spinal cord injury are equally appropriate for persons with brain and spinal cord tumors. These principles include the prevention of medical complications; the treatment of medical problems such as pain, spasticity, and neuropathic bowel and bladder; and the improvement of patients' mobility and activities of daily living. Rehabilitation specialists can help prevent complications, maximize function, and improve the quality of life for patients with central nervous system tumors.

Correlation of microvascular permeability derived from dynamic contrast-enhanced MR imaging with histologic grade and tumor labeling index: a study in human brain tumors

RATIONALE AND OBJECTIVES

Dynamic contrast material-enhanced magnetic resonance (MR) imaging may be used to quantify fractional blood volume (fBV) and microvascular permeability in human brain tumors. Hypothesis is that these measurements correlate with tumor histologic grade and immunohistologically assessed mitotic activity.

MATERIALS AND METHODS

Thirty-eight patients with newly diagnosed gliomas underwent MR imaging consisting of dynamic three-dimensional spoiled gradient-recalled acquisition in the steady state image sets following bolus injections of a single dose of gadodiamide. Signal intensity changes in blood and tissue were kinetically analyzed, yielding estimates of fBV and microvascular permeability (k). Tumor specimens were graded with the World Health Organization-II four-point grading score. MIB-1 immunohistochemical labeling (anti-Ki-67 monoclonal antibody) was performed in 22 patients to evaluate mitotic activity.

RESULTS

Histologic study revealed nine grade 2, 14 grade 3, and 15 grade 4 tumors. fBV ranged from 0.4% to 24%, k from -0.4 to 31.4 mL/100 cm3 x min, and MIB-1 labeling indexes from 1.7% to 42.8%. Correlation to the tumor grade was highest for permeability (r = 0.73), followed by the MIB-1 index (r = 0.63), and fBV (r = 0.48). Correlation between k and MIB-1 index was strong (r = 0.84). There was no statistically significant difference between the fBV of any of the groups. Despite some overlap between the permeability values of specific tumors from different grades, differences were statistically significant. The MIB-1 index was significantly different between grades 3 and 4 but not between grades 2 and 3.

CONCLUSION

Dynamic contrast-enhanced MR imaging allows noninvasive determination of tumor fBV and microvascular permeability k. k is more reliable than the MIB-1 labeling index for differentiating grade 2 from grade 3 tumors.

Low grade astrocytomas: controversies in management

Low grade astrocytomas are common brain neoplasms that primarily affect young adults. Although these patients often have a reasonably long survival, most will ultimately succumb to their tumours. Often the tumours progress to higher grade astrocytomas. The optimal management plan for these tumours is controversial and ranges from observation to macroscopic excision, radiotherapy and chemotherapy. The evidence for each of these approaches is presented in this review and a management algorithm is presented.

Analysis of proliferation and apoptosis in brain gliomas: prognostic and clinical value

With the introduction of new (immuno-)histochemical techniques it is now possible to assess rates of proliferation and apoptosis in brain gliomas using archival paraffin embedded material. As proliferation and apoptosis are related to tumour growth rate quantification of these processes has prognostic value and is related to tumour grading. In this study we assessed the proliferation rate by measuring the Ki-67 labelling index using the MIB-1 antibody (MIB-LI) and the apoptotic rate using the in situ labelling of DNA strand breaks with TUNEL (TUNEL-LI) in 315 supratentorial gliomas. MIB-LI and TUNEL-LI in astrocytomas (A) where significantly lower compared to anaplastic astrocytomas (AA), glioblastomas (GBM) and oligodendroglial tumours [oligodendrogliomas (O) and anaplastic oligodendrogliomas (AO)]. MIB-LI and TUNEL-LI were significantly lower in AA compared to GBM. In astrocytic tumours MIB-LI and TUNEL-LI appeared to be correlated. As the distinction between A and AA is of clinical value but can be difficult histomorphologically we analysed the prognostic value of MIB-LI and TUNEL-LI in gliomas with particular emphasis on A and AA. MIB-LI below 10% was of prognostic value in A and AA, O and AO but not in GBM on univariate survival analysis. TUNEL-LI was of no prognostic value. With multivariate survival analysis MIB-LI lost prognostic significance in O and AO. Astrocytomas with a gemistocytic component (AG) are similar to A with respect to survival and MIB-LI and TUNEL-LI. MIB-LI is of independent prognostic value in A and AA. Assessment of MIB-LI in A and AA can be used as an aid in distinguishing A and AA.

Immunohistochemical staining of DNA topoisomerase IIalpha in human gliomas

OBJECT

The enzyme DNA topoisomerase IIalpha (Topo IIalpha) was tested as a measure of cell proliferation in gliomas.

METHODS

Immunostaining for the Topo IIalpha and for the Ki-67 antigen (MIB-1 antibody) was performed in paraffin-embedded tissue sections obtained from 25 resected human gliomas. Additionally, cultured human glioma cells were subjected to simultaneous flow cytometry to determine Topo IIalpha and DNA content. Using flow cytometric analysis, the authors found that the Topo IIalpha antibody labeled cells in the S, G2, and M phases of the cell cycle and also those in some parts of the G0 and G1 phases. In histological sections, Topo IIalpha showed more distinct staining than MIB-1, particularly in older archival cases. The proliferative indices (PIs) based on cells staining for MIB-1 and Topo IIalpha correlated highly with one another (r = 0.96). The Topo IIalpha PI immunopositivity was seen in 4.07% of cells in the low-grade astrocytoma group, 11.97% in the anaplastic astrocytoma group, and 13.84% in the glioblastoma multiforme group, representing significant differences between low-grade astrocytoma and both anaplastic astrocytoma and glioblastoma. A Topo IIalpha PI less than 5% predicted longer patient survival (p = 0.003).

CONCLUSIONS

Immunostaining for Topo IIalpha represents a useful alternative to MIB-1 as a proliferative index in human gliomas.

Clinicopathologic study of 85 similarly treated patients with anaplastic astrocytic tumors. An analysis of DNA content (ploidy), cellular proliferation, and p53 expression

BACKGROUND

The biologic behavior of anaplastic (World Health Organization Grade III) astrocytomas and oligoastrocytomas is highly variable, ranging from rapid progression to prolonged survival. It is difficult to predict the outcome of an individual patient based on morphology alone.

METHODS

To determine the prognostic value of commonly used clinicopathologic markers, we reviewed our experience with 85 similarly treated patients enrolled in 3 North Central Cancer Treatment Group high grade glioma protocols. The pathology was comprised exclusively of primary anaplastic astrocytic tumors (66 astrocytomas and 19 oligoastrocytomas). Variables examined included patient age, morphologic type, preoperative performance score, extent of surgery, solitary versus multiple mitoses, DNA flow cytometric and image morphometric parameters, and expression of proliferating cell nuclear antigen, MIB-1, and p53 expression.

RESULTS

The study was comprised of 48 men and 37 women ranging in age from 14-79 years (median age, 47 years). Overall survival ranged from <1 month to >12 years (median, 21.6 months). Statistical analyses revealed that age accounted for the majority of this extensive variability in survival. The median survival times were 65. 5 months, 22.1 months, and 4.4 months, respectively, for the groups <40 years, 40-59 years, and >/=60 years, respectively (P < 0.0001). On univariate analyses, aneuploidy by flow cytometry and a low performance score also predicted a better survival (P values of 0.04 and 0.009, respectively). Statistical trends predicting a better survival were observed for patients with a solitary mitosis and p53 immunopositivity. However, only patient age remained significant in multivariate models.

CONCLUSIONS

In a small but relatively uniformly treated cohort of patients with anaplastic astrocytomas and oligoastrocytomas, patient age was associated strongly and inversely with overall survival. Once patient age was taken into account, the clinical and pathologic markers tested appeared to be of limited prognostic value.

The role of surgery in low grade gliomas

Several prognostic factors appear to be more important than treatment factors in determining the outcome of patients with low grade glioma. The role of surgery in establishing a histological diagnosis or in relieving neurological deficit is well established. The role of surgery in prolonging survival of patients with low grade glioma however, remains controversial, largely because studies in the literature on the management of this disease have been predominantly descriptive and observational, which precludes the setting of standards for the management of these patients. Several viable management options are discussed.

Proliferative activity as measured by MIB-1 labeling index and long-term outcome of visual pathway astrocytomas in children

Although most visual pathway tumors are low-grade gliomas their biologic behavior is highly unpredictable. In order to determine whether assessment of proliferative activity can assist in predicting tumor behavior, we studied the MIB-1 labeling indices (MIB-1 LIs) in surgical specimens and monitored tumor growth in 31 consecutive children operated on between 1978 and 1997. The MIB-1 LIs at diagnosis varied from 0-10.6% (mean +/- SD, 3.27 +/- 2.49%). Tumor progression occurred in 19 patients leading to death in seven, three of whom had neurofibromatosis type 1 (NF1). No association between MIB-1 LI at initial diagnosis and both progression free and overall survival was apparent. However, the MIB-1 LIs increased to 15.2% and 18% in two patients with NF1 who developed highly malignant gliomas 6 and 6.5 years after irradiation. In the remaining patients the MIB-1 LIs did not change significantly over time in a total of 17 repeat surgeries. Three patients with LIs of 6.8%, 10.6% and 8.8% are stable after 6, 4.5 and 3.5 years with partial resection, biopsy and subtotal resection, respectively, and no further therapy in the first two and chemotherapy in the latter. Three patients (10%) with LIs of 6.4%, 4.8% and 2.2% either presented with or developed leptomeningeal spread during follow-up. While MIB-1 LI does not appear to assist in clinical decision making patient numbers were too small to find out whether response to chemotherapy varies with proliferative potential.

p27/kip1 expression in human astrocytic gliomas

In the cell cycle, p27/kip1 acts as an inhibitory protein of cyclin-cdk complexes. p27/kip1 immunohistochemistry was performed in 50 gliomas (15 astrocytomas, 15 anaplastic astrocytomas and 20 glioblastomas) by a polyclonal antiserum. In the same tumours, proliferation marker Ki-67 was studied by MIB-1 antibody. For both, a labelling index (LI) was calculated after counting at least 1000 cells at x1000 magnification. p27 is diffusely and strongly expressed in astrocytomas (LI mean = 44.4%), whereas positive nuclei decrease in number and in staining intensity in anaplastic astrocytomas (LI mean = 5.86%) and glioblastomas (LI mean = 2.1%). An inverse correlation has been found between MIB-1 LI and p27 LI calculated in the same areas. Interestingly, in malignant gliomas the absence of p27 was independent from any histological feature of differentiation or anaplasia. p27 expression is thus reduced in malignant gliomas as in other malignancies. Since mutations of p27/kip1 are extremely rare, posttranslational changes are hypothesised also in astrocytic gliomas.