Accumulation of p53 and Ki-67 expression do not predict survival in patients with fibrillary astrocytomas or the response of these tumors to radiotherapy

[Gemistocytic astrocytomas]

Gemistocytic astrocytomas (GA) are a variant of diffuse astrocytomas GII (WHO, 2016). Like all diffuse astrocytomas, GA recur with time, which is often accompanied by malignant degeneretion into the anaplastic astrocytoma GIII or to the secondary glioblastoma GIV. However, the progression-free survival and overall survival in patients with GA is less than in patients with diffuse astrocytomas. Given that this group of patients, according to the WHO classification (2016), is classified as GII, patients with GA usually do not receive comprehensive treatment. We have conducted a thorough analysis of research on this problem for the period from 1956 to 2017. Differences in the histological pattern, immunohistochemical and molecular-genetic profiles, survival of patients with GA and diffuse astrocytomas GII are shown there. A clinical case of a patient with transformation of a diffuse astrocytoma in GA (GIII) and then into a secondary glioblastoma is presented.

The role of neuropathology in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

TARGET POPULATION

Adult patients (age ≥18 years) who have suspected low-grade diffuse glioma.

QUESTION

What are the optimal neuropathological techniques to diagnose low-grade diffuse glioma in the adult?

RECOMMENDATION

LEVEL I: Histopathological analysis of a representative surgical sample of the lesion should be used to provide the diagnosis of low-grade diffuse glioma.

LEVEL III

Both frozen section and cytopathologic/smear evaluation should be used to aid the intra-operative assessment of low-grade diffuse glioma diagnosis. A resection specimen is preferred over a biopsy specimen, to minimize the potential for sampling error issues.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is testing for IDH1 mutation (R132H and/or others) warranted? If so, is there a preferred method?

RECOMMENDATION

LEVEL II

IDH gene mutation assessment, via IDH1 R132H antibody and/or IDH1/2 mutation hotspot sequencing, is highly-specific for low-grade diffuse glioma, and is recommended as an additional test for classification and prognosis.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is testing for 1p/19q loss warranted? If so, is there a preferred method?

RECOMMENDATION

LEVEL III

1p/19q loss-of-heterozygosity testing, by FISH, array-CGH or PCR, is recommended as an additional test in oligodendroglial cases for prognosis and potential treatment planning.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is MGMT promoter methylation testing warranted? If so, is there a preferred method?

RECOMMENDATION

There is insufficient evidence to recommend methyl-guanine methyl-transferase (MGMT) promoter methylation testing as a routine for low-grade diffuse gliomas. It is recommended that patients be enrolled in properly designed clinical trials to assess the value of this and related markers for this target population.

TARGET POPULATION

Patients with histologically-proven WHO grade II diffuse glioma.

QUESTION

In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is Ki-67/MIB1 immunohistochemistry warranted? If so, is there a preferred method to quantitate results?

RECOMMENDATION

LEVEL III

Ki67/MIB1 immunohistochemistry is recommended as an option for prognostic assessment.

The role of radiotherapy in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

QUESTIONS

(1) What is the optimal role of external beam radiotherapy in the management of adult patients with newly diagnosed low-grade glioma (LGG) in terms of improving outcome (i.e., survival, complications, seizure control or other reported outcomes of interest)? (2) Which radiation strategies (dose, timing, fractionation, stereotactic radiation, brachytherapy, chemotherapy) improve outcomes compared to standard external beam radiation therapy in the initial management of low grade gliomas in adults? (3) Do specific factors (e.g., age, volume, extent of resection, genetic subtype) identify subgroups with better outcomes following radiation therapy than the general population of adults with newly diagnosed low-grade gliomas?

TARGET POPULATION

These recommendations apply to adults with newly diagnosed diffuse LGG.

RECOMMENDATIONS

OUTCOMES IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level I Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong progression free survival, irrespective of extent of resection. Level II Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults as an equivalent alternative to observation in preserving cognitive function, irrespective of extent of resection. Level III Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults to improve seizure control in patients with epilepsy and subtotal resection. Level III Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong overall survival in patients with subtotal resection. Level III Consideration of the risk of radiation induced morbidity, including cognitive decline, imaging abnormalities, metabolic dysfunction and malignant transformation, is recommended when the delivery of radiotherapy is selected in the management of newly diagnosed low-grade glioma in adults. STRATEGIES OF RADIOTHERAPY IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA: Level I Lower dose radiotherapy is recommended as an equivalent alternative to higher dose immediate postoperative radiotherapy (45-50.4 vs. 59.4-64.8 Gy) in the management of newly diagnosed low-grade glioma in adults with reduced toxicity. Level III Delaying radiotherapy until recurrence or progression is recommended as an equivalent alternative to immediate postoperative radiotherapy in the management of newly diagnosed low-grade glioma in adults but may result in shorter time to progression. Level III The addition of chemotherapy to radiotherapy is not recommended over whole brain radiotherapy alone in the management of low-grade glioma, as it provides no additional survival benefit. Level III Limited-field radiotherapy is recommended over whole brain radiotherapy in the management of low-grade glioma. Level III Either stereotactic radiosurgery or brachytherapy are recommended as acceptable alternatives to external radiotherapy in selected patients. PROGNOSTIC FACTORS IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level II It is recommended that age greater than 40 years, astrocytic pathology, diameter greater than 6 cm, tumor crossing the midline and preoperative neurological deficit be considered as negative prognostic indicators when predicting overall survival in adult low grade glioma patients treated with radiotherapy. Level II It is recommended that smaller tumor size, extent of surgical resection and higher mini-mental status exam be considered as positive prognostic indicators when predicting overall survival and progression free survival in patients in adult low grade glioma patients treated with radiotherapy. Level III It is recommended that seizures at presentation, presence of oligodendroglial histological component and 1p19q deletion (along with additional relevant factors-see Table 1) be considered as positive prognostic indicators when predicting response to radiotherapy in adults with low grade gliomas. Level III It is recommended that increasing age, decreasing performance status, decreasing cognition, presence of astrocytic histological component (along with additional relevant factors (see Tables 1, 2) be considered as negative prognostic indicators when predicting response to radiotherapy.

The molecular biology of WHO grade II gliomas

The WHO grading scheme for glial neoplasms assigns Grade II to 5 distinct tumors of astrocytic or oligodendroglial lineage: diffuse astrocytoma, oligodendroglioma, oligoastrocytoma, pleomorphic xanthoastrocytoma, and pilomyxoid astrocytoma. Although commonly referred to collectively as among the "low-grade gliomas," these 5 tumors represent molecularly and clinically unique entities. Each is the subject of active basic research aimed at developing a more complete understanding of its molecular biology, and the pace of such research continues to accelerate. Additionally, because managing and predicting the course of these tumors has historically proven challenging, translational research regarding Grade II gliomas continues in the hopes of identifying novel molecular features that can better inform diagnostic, prognostic, and therapeutic strategies. Unfortunately, the basic and translational literature regarding the molecular biology of WHO Grade II gliomas remains nebulous. The authors' goal for this review was to present a comprehensive discussion of current knowledge regarding the molecular characteristics of these 5 WHO Grade II tumors on the chromosomal, genomic, and epigenomic levels. Additionally, they discuss the emerging evidence suggesting molecular differences between adult and pediatric Grade II gliomas. Finally, they present an overview of current strategies for using molecular data to classify low-grade gliomas into clinically relevant categories based on tumor biology.

Low-grade astrocytomas: the prognostic value of fibrillary, gemistocytic, and protoplasmic tumor histology

OBJECT

Low-grade astrocytomas are slow-growing, infiltrative gliomas that over time may progress into more malignant tumors. Various factors have been shown to affect the time to progression and overall survival including age, performance status, tumor size, and the extent of resection. However, more recently it has been suggested that histological subtypes (fibrillary, protoplasmic, and gemistocytic) may impact patient outcome. In this study the authors have performed a large comparative population-based analysis to examine the characteristics and survival of patients with the various subtypes of WHO Grade II astrocytomas.

METHODS

Patients diagnosed with fibrillary, protoplasmic, and gemistocytic astrocytomas were identified through the Surveillance, Epidemiology, and End Results (SEER) database. The chi-square test and Student t-test were used to evaluate differences in patient and treatment characteristics between astrocytoma subtypes. Kaplan-Meier analysis was used to assess overall survival, and the log-rank test was used to evaluate the differences between survival curves. Univariate and multivariate analyses were also performed to determine the effect of various patient, tumor, and treatment variables on overall survival.

RESULTS

A total of 500 cases were included in the analysis, consisting of 326 fibrillary (65.2%), 29 protoplasmic (5.8%), and 145 gemistocytic (29%) variants. Gemistocytic astrocytomas presented at a significantly older age than the fibrillary variant (46.8 vs 37.7 years, p < 0.0001), with protoplasmic and fibrillary subtypes having a similar age. Although protoplasmic and fibrillary variants underwent radiotherapy at similar rates, gemistocytic tumors more frequently received radiotherapy (p = 0.0001). Univariate analysis revealed older age, larger tumor size, and the use of radiotherapy to be poor prognostic factors, with resection being associated with improved survival. The gemistocytic subtype (hazard ratio [HR] 1.62 [95% CI 1.27-2.07], p = 0.0001) also resulted in significantly worse survival than fibrillary tumors. Bivariate analyses demonstrated that older age, the use of radiotherapy, and resection significantly influenced median survival. Tumor subtype also affected median survival; patients who harbored gemistocytic tumors experienced less than half the median survival of fibrillary and protoplasmic tumors (38 vs 82 months, p = 0.0003). Multivariate analysis revealed increasing age (HR 1.05 [95% CI 1.04-1.05], p < 0.0001), larger tumor size (HR 1.02 [95% CI 1.01-1.03], p = 0.0002), and the use of resection (HR 0.70 [95% CI 0.52-0.94], p = 0.018) to be independent predictors of survival. Examination of tumor subtype revealed that the gemistocytic variant (HR 1.30 [95% CI 0.98-1.74], p = 0.074) was associated with worse patient survival than fibrillary tumors, although this only approached significance. The protoplasmic subtype did not affect overall survival (p = 0.33).

CONCLUSIONS

Gemistocytic tumor histology was associated with worse survival than fibrillary and protoplasmic astrocytomas. As protoplasmic astrocytomas have a survival similar to fibrillary tumors, there may be limited utility to the identification of this rare variant. However, increased attention should be paid to the presence of gemistocytes in low-grade gliomas as this is associated with shorter time to progression, increased malignant transformation, and reduced overall survival.

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.

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.

Assessment and prognostic significance of mitotic index using the mitosis marker phospho-histone H3 in low and intermediate-grade infiltrating astrocytomas

Distinguishing between grade II and grade III diffuse astrocytomas is important both for prognosis and for treatment decision-making. However, current methods for distinguishing between grades based on proliferative potential are suboptimal, making identification of clear cutoffs difficult. In this study, we compared the results from immunohistochemical staining for phospho-histone H3 (pHH3), a specific marker of cells undergoing mitosis, with standard mitotic counts (number of mitoses/10 high-power fields) and MIB-1 labeling index values for assessing proliferative activity. We tested the relationship between pHH3 staining and tumor grade and prognosis in a retrospective series of grade II and III infiltrating astrocytomas from a single institution. The pHH3 index (per 1000 cells), MIB-1 index (per 1000 cells), and number of mitoses per 10 high-power fields were determined for each of 103 cases of grade II and III diffuse astrocytomas from patients with clinical follow-up. pHH3 staining was found to be a simple and reliable method for identifying mitotic figures, allowing a true mitotic index to be determined. The pHH3 mitotic index was significantly associated both with the standard mitotic count and with the MIB-1 index. Univariate analyses revealed that all 3 measurements of proliferation were significantly associated with survival. However, the pHH3 mitotic index accounted for a larger proportion of variability in survival than standard mitotic count or MIB-1/Ki-67 labeling index. After adjusting for age, extent of resection, and performance score, the pHH3 mitotic index remained an independent predictor of survival. Thus, pHH3 staining provides a simple and reliable method for quantifying proliferative potential and for the stratification of patients with diffuse astrocytomas into typical grade II and III groups. These results also suggest that pHH3 staining may be a useful method in other neoplasms in which accurate determination of proliferation potential is relevant to tumor grading or clinical treatment decision-making.

Spontaneous regression of residual low-grade cerebellar pilocytic astrocytomas in children

BACKGROUND

Cerebellar low-grade astrocytomas (CLGAs) of childhood are benign tumours and are usually curable by surgical resection alone or combined with adjuvant radiotherapy.

OBJECTIVE

To undertake a retrospective study of our children with CLGA to determine the optimum schedule for surveillance imaging following initial surgery. In this report we describe the phenomenon of spontaneous regression of residual tumour and discuss its prognostic significance regarding future imaging.

MATERIALS AND METHODS

A retrospective review was conducted of children treated for histologically proven CLGA at Great Ormond Street Hospital from 1988 to 1998.

RESULTS

Of 83 children with CLGA identified, 13 (15.7%) had incomplete resections. Two children with large residual tumours associated with persistent symptoms underwent additional treatment. Eleven children were followed by surveillance imaging alone for a mean of 6.83 years (range 2-13.25 years). Spontaneous tumour regression was seen in 5 (45.5%) of the 11 children. There were no differences in age, gender, symptomatology, histological grade or Ki-67 fractions between those with spontaneous tumour regression and those with progression. There was a non-significant trend that larger volume residual tumours progressed.

CONCLUSIONS

Residual tumour followed by surveillance imaging may either regress or progress. For children with residual disease we recommend surveillance imaging every 6 months for the first 2 years, every year for years 3, 4 and 5, then every second year if residual tumour is still present 5 years after initial surgery. This would detect not only progressive or recurrent disease, but also spontaneous regression which can occur later than disease progression.

Minichromosome Maintenance Protein 3 Elicits a Cancer-Restricted Immune Response in Patients with Brain Malignancies and Is a Strong Independent Predictor of Survival in Patients with Anaplastic Astrocytoma

Purpose: The identification of new molecular markers in astrocytic tumors may help to understand the biology of these tumors in more detail. Informative tumor markers may represent prognostic factors for response to therapy and outcome as well as potential targets for novel anticancer therapies.

Experimental Design: Tumor-associated antigens were identified by immunoscreening of a human glioma cDNA expression library with allogeneic sera from patients with diffuse astrocytoma (WHO grades 2-4). The expression of one of the identified antigens, the replication licensing factor minichromosome maintenance protein 3 (MCM3), was analyzed by immunohistochemistry in 142 primary and 27 recurrent astrocytomas (WHO grades 2-4). In addition, 98 serum specimens from patients with primary and secondary brain malignancies and 30 serum specimens from healthy controls were examined by serologic immunoscreening for immunoreactivity with MCM3.

Results: MCM3 is overexpressed in human astrocytic tumors and elicits a cancer-restricted humoral immune response in 9.3% (9 of 97) of patients with brain tumors (n = 95) and brain metastases (n = 2) but not in healthy controls. Expression of MCM3 in diffuse astrocytoma is significantly associated with age (P &lt; 0.001), histologic grade (P &lt; 0.001), time to recurrence (P = 0.01), and expression of the proliferation marker Ki-67 (P &lt; 0.001) but not with sex (P = 0.800). Univariate and multivariate Cox regression analysis confirmed MCM3 expression as an independent predictor of poor outcome in astrocytoma patients (P &lt; 0.001 for both).

Conclusions: MCM3 may represent a glioma-associated antigen with significant prognostic role as well as have some potential as a target for cancer-directed therapy.

ORC-associated replication factors as biomarkers for cancer

Early detection and treatment of cancer are of central importance to improving patient prognoses. Traditional biomarkers of cell proliferation, such as Ki-67 and PCNA, have had a mixed clinical track record, proving to be good indicators of certain types of cancers but of limited use for many others. Recently, human counterparts of replication factors originally identified in budding yeast have shown great promise as new cancer biomarkers. Each of these factors has been shown to interact with the origin recognition complex (ORC) in yeast, and each has an essential role in the initiation of DNA replication. Studies with minichromosome maintenance (MCM) family proteins show that their levels are upregulated in tumor cells and are much better indicators of a wide variety of cancers than traditional biomarkers. Similarly encouraging results have been obtained in preliminary studies examining Cdc6 protein and Cdc7 kinase transcript levels in normal and cancerous cells.

Low-grade glioma: supratentorial astrocytoma, oligodendroglioma, and oligoastrocytoma in adults

Low-grade glioma is not a single diagnosis but a category of biologically diverse neoplasms. They are indolent, progressive, and, following anaplastic transformation, invariably fatal. Neuro-oncologists have not established a treatment standard for these tumors. However, it is clear that "low-grade" is not synonymous with "benign," and treatment is required sometime in the course of the disease. Previously, achieving a consensus had been limited by a lack of class I evidence. Physicians treated patients based on retrospective series and personal experience. Currently, results from prospective clinical trials are becoming available. These studies have provided data that may serve as treatment guidelines. Additional results regarding the identification of prognostic variables have raised more questions to be answered. Attention is now directed to the importance of translational research to better define these neoplasms. In the future, it will be necessary to distinguish among low-grade gliomas and identify therapies that may differ between them.

Loss of heterozygosity of a locus in the chromosomal region 17p13.3 is associated with increased cell proliferation in astrocytic tumors

We had previously reported that loss of heterozygosity (LOH) of the D17S379 locus on 17p13.3 was significantly more frequent in high-grade gliomas (anaplastic astrocytoma, AA; glioblastoma multiforme, GBM) than in those of a low-grade diffuse astrocytoma (DA); however, this was independent of alterations at the TP53 locus, We also showed that LOH of D17S379 was associated with positive staining for p53 protein on immunohistochemistry, but LOH of the TP53 gene had no such association. In this work we show that cell proliferation as determined by MIB-1 labeling index (LI) was significantly higher in tumors with LOH of D17S379 than those with no LOH (NLOH). In accord with our previous results, p53 protein immunopositivity was also associated with increased MIB-1 LI; however, we observed no such association of LI with TP53 LOH. The results further confirm that alteration of one or more putative tumor suppressor loci at 17p13.3 is associated with increased proliferation in astrocytic tumors.

Promoter hypermethylation of the DNA repair gene O6-methylguanine-DNA methyltransferase is an independent predictor of shortened progression free survival in patients with low-grade diffuse astrocytomas

The O6-methylguanine-DNA methyltransferase (MGMT) plays a major role in repairing DNA damage from alkylating agents. In several human neoplasms including low-grade diffuse astrocytomas, promoter hypermethylation of MGMT has been shown to correlate with an increased frequency of p53 mutation. In the present study, we analyzed MGMT promoter methylation by the methylation-specific PCR in 49 newly diagnosed WHO grade II astrocytomas and evaluated its clinical usefulness. MGMT promoter methylation was found in 21 (43%) of the 49 tumors. A tight correlation existed between MGMT methylation and p53 protein accumulation (P=0.0424). The presence of MGMT methylation was significantly associated with a shorter progression free survival (PFS) on both univariate analysis (P=0.0014) and multivariate analysis (P=0.0081). It was a more powerful determinant of the PFS than age, sex, performance status, proliferative activity, or p53 expression, and was independent of the extent of surgery. In terms of the overall survival, MGMT methylation demonstrated a prognostic utility in the univariate analysis but not in the multivariate analysis. The present findings indicate that aberrant methylation of the MGMT promoter independently augurs for an unfavorable clinical course in patients with low-grade diffuse astrocytomas. Since the presence of MGMT methylation is expected to predict an increased sensitivity to alkylating chemotherapeutic agents, earlier chemotherapy could serve to improve an unfavorable natural history in tumors with MGMT methylation.

Treatment of low-grade diffuse astrocytomas by surgery and human fibroblast interferon without radiation therapy

Low-grade diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. However, a substantial proportion undergoes dedifferentiation to a more malignant phenotype. Considerable controversy exists as to the best therapeutic management for patients with such tumors. Over the past decade, we have applied human fibroblast interferon (HFIF) therapy without radiation therapy to low-grade astrocytomas. We investigated 28 patients with WHO grade II astrocytomas of the cerebral hemispheres treated by surgery plus HFIF therapy. The overall response rate to the HFIF therapy was 36%. All side-effects of HFIF were transient, tolerable and manageable. The 5-year progression free survival and overall survival probabilities were 65% and 96%, respectively. Although our data from small cohort of patients may have modest value, our results suggest that HFIF may be useful in treating low-grade diffuse astrocytomas.

Morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery

Object. The purpose of this study was to demonstrate positron emission tomography (PET), histological, and immunohistochemical data supporting the notion of morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery (GKS).

Methods. The 11C- methionine-PET activity, Ki-67 labeling index (LI), and p53 protein expression were examined using immunohistochemical methods to assess tumor proliferative capacity. Tissue samples were obtained before and after radiosurgery in a patient with a malignant (Grade III) cerebellar astrocytoma.

Positron emission tomography scans obtained 5.5 months following radiosurgery were suggestive of decreased tumor proliferative capacity and radionecrosis. Histological examination of tumor tissue removed 42 months before GKS was characteristic of a diffuse Grade III astrocytoma in every part of the resected tumor. Similar material removed 6 months after GKS was consistent with a Grade II astrocytoma in the great majority of the resected tumor.

Conclusions. Histopathological examination showed positive phenotypic modification (redifferentiation) consistent with a Grade II astrocytoma in the majority of tumor specimens after radiosurgery. After GKS both the Ki-67 LI and p53 reaction decreased considerably as did 11C methionine uptake. Because p53 is one of the essential genes involved in the radiation response, mutations induced by the ionizing effect of gamma rays might promote partial repair of this gene's tumor suppressor function.

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.

p53 in nonneoplastic central nervous system lesions: an immunohistochemical and genetic sequencing study

OBJECTIVE

Immunostaining for p53 commonly is considered a marker of neoplasia. Previous studies of nonneoplastic processes have yielded conflicting results.

METHODS

To test the assumption that p53 immunoreactivity indicates neoplasia, we examined 60 formalin-fixed, paraffin-embedded biopsies of nonneoplastic central nervous system lesions, including gliosis (n = 12), infarction (n = 9), demyelinating disease (n = 23), progressive multifocal leukoencephalopathy (n = 11), and herpes simplex virus encephalitis (n = 5). Diffuse astrocytomas (n = 50) of World Health Organization Grades 2 to 4 also were studied, as were six control autopsy brains. The avidin-biotin-peroxidase complex method was used with commercially available monoclonal antisera to both p53 (clone DO7; Dako, Carpinteria, CA) and mdm2 (Dako), a protein known to stabilize p53. Two samples of each nonneoplastic lesion also were subjected to deoxyribonucleic acid isolation, amplification, and sequencing of exons 5 to 8 of TP53.

RESULTS

Although it was low level in most instances, p53 immunoreactivity was noted in all but normal control samples. In reactive lesions, staining was largely observed in astrocytes and histiocytes. Scant oligodendroglia also were labeled in demyelinating disease. The progressive multifocal leukoencephalopathy samples revealed exceptionally strong staining in astrocytes and infected oligodendrocytes. Staining also was noted in occasional endothelial cells and neurons, and in rare lymphocytes. Immunoreactivity for mdm2, studied only in nonneoplastic lesions, was moderate to strong in all cases and limited to reactive astrocytes and histiocytes. No TP53 mutations were noted in the nonneoplastic lesions studied. To some extent, all astrocytomas exhibited p53 immunopositivity, particularly high-grade lesions.

CONCLUSION

p53 immunoreactivity is not limited to astrocytomas, but it can be observed in lesions that often are mistaken for glioma. No TP53 mutations accompany p53 expression in nonneoplastic lesions, and mdm2 may be responsible for persistence of p53 expression in these processes.

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.

Ki67 protein: the immaculate deception?

This article updates our previous review of Ki67 published in Histopathology 10 years ago. In this period the numbers of papers published featuring this antibody has increased 10-fold from 338 to 3489 indicating the considerable enthusiasm with which this antibody has been studied. This review attempts to provide an update on the characterization of the Ki67 protein, its function and its use as a prognostic or diagnostic tool.

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.

MIB-1 staining index of pediatric meningiomas

OBJECTIVE

For adult meningiomas, the staining index (SI) for the anti-Ki-67 monoclonal antibody MIB-1 is well correlated with histological atypia and tumor recurrence. MIB-1 SIs for meningiomas in the pediatric population have not been previously reported. Meningiomas tend to be more histologically aggressive and to recur more frequently in children, compared with adults. The objectives of this study were to determine whether MIB-1 SIs are correlated with pathological atypia and recurrence among pediatric meningiomas and to compare the MIB-1 SIs of pediatric meningiomas with those of adult meningiomas.

METHODS

MIB-1 SIs were assessed on paraffin-embedded sections of 14 pediatric meningiomas (patient age, 2-17 yr), 5 of which contained atypical or malignant features. For comparison with benign pediatric meningiomas, MIB-1 SIs were also assessed on paraffin-embedded sections of 14 adult meningiomas (patient age, 38-90 yr), none of which displayed atypical or malignant features or recurred within a 5-month median follow-up period.

RESULTS

MIB-1 SIs of pediatric meningiomas ranged from 1.2 to 31.6% (median, 9.1%). Significant differences were observed between the MIB-1 SIs for tumors with atypical or malignant features (median, 12.3%; range, 7.0-31.6%) and those for tumors without atypia (median, 7.0%; range, 1.2-12.6%; P = 0.045). There were six recurrences after gross total resection, during a 36.5-month median follow-up period. All five of the tumors with pathological atypia recurred; one tumor without atypia recurred. Significant differences were observed between MIB-1 SIs for nonrecurrent tumors (median, 6.6%; range, 1.2-12.2%) and those for recurrent tumors (median, 12.5%; range, 7.0-31.6%; P = 0.012). The median MIB-1 SI for adult control specimens was 8.8% (range, 1.2-19.3%), which did not differ significantly from that for pediatric meningiomas without atypia (P = 0.68).

CONCLUSION

For this cohort of pediatric meningiomas, pathological atypia and the tendency to recur were correlated with elevated MIB-1 SIs. The median MIB-1 SI for pediatric meningiomas without histological atypia did not differ significantly from that for adult meningiomas without atypia, suggesting that the more aggressive clinical features of meningiomas in children may be attributable to factors other than the rate of cellular proliferation.

TP53 deleted cells in de novo glioblastomas using fluorescence in situ hybridization

Glioblastoma (GBM) has been known to have two distinct genetic pathways of tumorigenesis. Secondary GBM shows frequent TP53 mutation, but de novo (primary) GBM is usually independent of TP53 alteration. However, the subpopulation of TP53 altered cells in the latter tumor is obscure. In order to assess TP53 deleted cells in de novo GBM quantitatively, we performed dual color fluorescence in situ hybridization (FISH) for TP53 and centromere 17 in nine cases of de novo GBM with frozen surgical materials. Single TP53 signal cells indicating TP53 deletion were recognized in 8.7-35.6% (mean, 21.3%) among the nine cases. In addition, immunohistochemistry was performed for the Ki-67 antigen (MIB-1) and p53 protein in all nine cases. Labeling indices (LI) of MIB-1 ranged from 2.8 to 46.9% (mean, 20.8%). Between the group with the more dense subpopulation of TP53 deleted cells (15% or more) by FISH and the group with less subpopulation than the former, these LI of MIB-1 demonstrated statistically significant difference (respective means, 28.2% and 6.1%; P < 0.05). Conversely, LI of p53 protein shown to be 0-50.9% (mean, 24.9%) had no correlation with the subpopulation of TP53 deleted cells by FISH. Four cases who had higher LI of p53 protein (mean, 39.7%) than the subpopulation of TP53 deleted cells (mean, 12.7%), respectively, indicated the presence of many p53 protein immunoreactive cells without TP53 deletion. These results suggest that: (i) de novo GBM also has subpopulation of TP53 deleted cells; (ii) TP53 alteration, which may not be a major event, participates in cell proliferation of de novo GBM; and (iii) de novo GBM tends to have accumulation of wild-type p53 protein.

Postoperative radiotherapy of astrocytomas

Astrocytomas account for the majority of primary brain tumors. Low-grade tumors are slowly growing tumors with relatively long overall survival. However, a high percentage of these tumors transform to more malignant, high-grade tumors. High-grade gliomas (anaplastic astrocytomas and glioblastoma multiforme) have a poor prognosis. Treatment options are capable of prolonging the natural history of the disease, but the long-term survival is poor. This review discusses the different postoperative treatment options and the prognostic factors in low- and high-grade astrocytomas.

Clinicopathological features, MIB-1 labeling index and apoptotic index in recurrent astrocytic tumors

This is a study of 64 cases of recurrent astrocytic tumors of all four WHO grades wherein a comparative evaluation of initial vs. recurrent tumor was done with respect to histological grading, MIB-1 labeling index (LI) and apoptotic index (AI). The aim was to identify factor/s that could influence interval to recurrence and/or malignant progression. Recurrence was noted in all grades and upon recurrence, 93.3% of grade II (low grade diffuse) astrocytomas and 63.6% of grade III anaplastic astrocytomas underwent malignant progression. However, none of the Grade I tumors showed evidence of malignant progression. Though interval to recurrence varied considerably, there was a correlation with histological grade of the initial tumor in that grade I and II tumors had a significantly longer mean interval to recurrence (43 months and 54.8 months respectively) as compared to grade III and IV (glioblastoma multiforme) tumors (17.6 and 12.8 months respectively). The interval to recurrence was also longer for grade II and III tumors which showed progression on recurrence (55.3 months for Grade II->Grade III; 54 months for Grade II->Grade IV and 20.6 months for Grade III->IV) as compared to tumors which recurred to the same grade (12.5 months for Grade III->Grade III and 12.8 months for Grade IV->Grade IV). A statistically significant inverse correlation of MIB-1 LI with interval to recurrence was noted. Higher the MIB-1 LI, shorter was the interval to recurrence. Further a cut off MIB-1 LI value of 2.8% could be proposed in predicting recurrence free survival. Interestingly, MIB-1 LI of grade II tumors, which had progressed to grade IV was significantly higher than MIB-1 LI of grade II tumors which had progressed to grade III. Thus, this study establishes the potential role of MIB-1 LI of the initial tumor in determining interval to recurrence. However, apoptotic index has no role in predicting either interval to recurrence or malignant progression.

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.

Brain tumor invasion rate measured in vitro does not correlate with Ki-67 expression

The need for more accurate prediction of the biological behavior of brain tumors has lead to the use of immunohistochemical methods for assessment of proliferating cell nuclear antigens such as Ki-67. There is a variable association of glioma Ki-67 labeling index with patient survival. Brain invasion by individual tumor cells also defines biological aggressiveness, and can be assessed in vitro. Further, proliferation and migration seem to be mutually exclusive behaviors for a given cell at a point in time. We studied the relationship between Ki-67 labeling index and invasion rate in a group of 10 gliomas, and 2 meningiomas. Human tumor spheroids obtained from operative specimen were co-cultured with fetal rat brain aggregates, and invasion rate was measured by confocal microscopic observation. There was no correlation between two measures of invasion and Ki-67 labeling. This finding supports the dichotomous nature of glioma proliferation and invasion, and may in part explain the limited usefulness of proliferation marker labeling.

The challenge of p53 as prognostic and predictive factor in gliomas

In recent years, increasing interest in genetic abnormalities and biologic factors such as the tumour suppressor gene p53 as possible predictive and prognostic factor in gliomas has emerged. Inactivation of p53 can result in resistance to apoptosis, one of the mechanisms thought to explain the failure to respond to DNA-damaging agents. Thus, inactivation of p53 might be associated with a worse prognosis. Considering the inconsistent results of several recent studies, it has remained controversial whether p53 actually can be related to response to treatment and patients' prognosis. Therefore, a systematic review of the literature was performed, which included 28 publications. Techniques for assessing the inactivation of p53 varied widely. Overall, approximately 50% or more of astrocytoma specimens evaluated by immunohistochemistry stained positively for p53, regardless of histologic grade. Eight studies were restricted to comparably treated patients within a single histologic group. In most instances, non-restrictive inclusion criteria and use of statistical methods, which were not sufficient to correct the possible bias, make it difficult to reach unequivocal conclusions. However, it appears that the prognostic information of p53 is at best marginal, especially when compared to established parameters such as grading, age, etc. Its predictive value, which most likely is rather limited too, can hardly be judged without prospective studies also evaluating other biological factors as well as end-points other than time to radiological progression.