Histological grading and bromodeoxyuridine labeling index of astrocytomas. Comparative study in a series of 60 cases

Activation of caspase-9 with irradiation inhibits invasion and angiogenesis in SNB19 human glioma cells

Glioblastoma multiforme, the most common brain tumor, typically exhibits markedly increased angiogenesis, which is crucial for tumor growth and invasion. Antiangiogenic strategies based on disruption of the tumor microvasculature have proven effective for the treatment of experimental brain tumors. Here, we have overexpressed human caspase-9 by stable transfection in the SNB19 glioblastoma cell line, which normally expresses low levels of caspase-9. Our studies revealed that overexpression of caspase-9 coupled with radiation has a synergistic effect on the inhibition of glioma invasion as demonstrated by Matrigel assay (> 65%). Furthermore, sense caspase stable clones cocultured with fetal rat brain aggregates along with radiation showed complete inhibition as compared to the parental and vector controls. During in vitro angiogenesis, SNB19 cells cocultured with human microvascular endothelial cells (HMEC) showed vascular network formation after 48-72 h. In contrast, these capillary-like structures were inhibited when HMEC cells were cocultured with sense caspase stable SNB19 cells. This effect was further enhanced by radiation (5 Gy). Signaling mechanisms revealed that apoptosis is induced by cleavage of caspase-9 by radiation, loss of mitochondrial membrane potential and activation of caspase-3. These results demonstrate that activation of caspase-9 disrupts glioma cell invasion and angiogenesis in vitro. Hence, overexpression of proapoptotic molecules such as caspase-9 may be an important determinant of the therapeutic effect of radiation in cancer therapy.

Cell proliferation and tumors of the central nervous system, part II: radiolabeling, cytometric, and immunohistochemical techniques

A variety of techniques have been developed to evaluate cell proliferation. Many of these methods provide a more accurate means of assessing the true proliferation rate of a given neoplasm, as compared with the simple assessment of mitotic activity. Similar to the evaluation of mitotic activity, these methods are also subject to limitations associated with tumor heterogeneity and interobserver variability. This paper reviews a variety of methodologies including radiolabeling, flow cytometric, and immunohistochemical that have been used in recent years to evaluate cell proliferation in brain neoplasms. Factors that affect these methodologies and their practical application to routine practice of diagnostic neuropathology will be explored.

PCNA and Ki-67 in central nervous system tumors: correlation with the histological type and grade

Determination of proteins in the control of proliferation in normal cells helps a better understanding of cellular transformation and proliferation mechanisms. Measurement of proliferative activity is important in determining the tumor grade, recurrence span and malignancy. Proliferating cell nuclear antigen (PCNA) and Ki-67 are two of the nuclear markers used to demonstrate the proliferative phase of the cell cycle. In the present study, 63 central nervous system (CNS) tumors of various histologic types, diagnosed in Cukurova University Medical Faculty. Department of Pathology and graded according to WHO grading system were examined for PCNA and Ki-67 monoclonal antibodies using immunohistochemistry. Results were analyzed with statistical methods. Distribution of PCNA and Ki-67 LI (labeling index) values were determined for different tumor types. The highest PCNA and Ki-67 LI values were detected in medulloblastoma, malignant meningioma, primitive neuroectodermal tumor (PNET) and glioblastoma (GBM) groups, while pilocytic astrocytoma, meningioma, craniopharyngioma and oligodendroglioma showed the lowest values. In such tumors, the correlation between the increasing grade and PCNA and Ki-67 LI values were statistically significant. A correlation between the clinical outcome and Ki-67 and PCNA LI values was also detected. Conclusively, both markers can be used to evaluate the tumor grade and to asses the possibility of recurrence and malignancy in CNS tumors.

Biologic parameters that correlate with the prognosis of human gliomas

Much clinical and biologic data have been processed in the search for useful objective parameters to predict brain tumor behavior. Seventy cases of astrocytic glioma collected by a single clinical team were studied using a full complement of clinical procedures: follow up (7 years), histologic analysis, DNA content estimation, and cell kinetics by flow cytometry. Proliferating cell nuclear antigen (PCNA) was determined by immunocytochemical-coupling flow cytometry (PFC) and also by counting under light microscopy (PIHC). A statistical evaluation was carried out to establish the usefulness of several parameters for glioma prognosis. The cases were histologically classified as 14 low-grade astrocytomas, 20 anaplastic astrocytomas, and 36 glioblastomas multiforme. The survival curve showed significant differences between histologic groups. Diploid populations were more frequent in low-grade astrocytomas, and aneuploid tumors often had increased S-phase and proliferative fractions. The PCNA-labeled index (PCNA-LI) increased with malignancy and correlated with histologic grading (P = 0.01). The PCNA-LI and age segregated low- from high-grade astrocytomas (including anaplastic astrocytoma and glioblastoma multiforme), but none of the variables considered differentiated anaplastic astrocytoma from glioblastoma multiforme. The Cox regression test displayed significant values for age, histologic diagnosis, and PCNA determinations when considered in tandem. Discriminant analysis obtained a function integrating age and specifically PIHC-LI to help in the prognosis of doubtful cases. The results emphasize the importance of parameters integrating different variables in an attempt to provide an accurate prognosis, the most significant being age, histopathologic diagnosis, and the proliferative fraction determined by PCNA.

Overexpression of cyclin A and cyclin B1 proteins in astrocytomas

BACKGROUND

Cyclins are proteins that are expressed during the progression of a normal cell through the cell cycle. In a number of cancers, overexpression of cyclin A and cyclin B1 proteins has been reported, and in some instances the levels of expression correlated well with the grades of malignancy. The expression of cyclin A and cyclin B1 proteins in astrocytoma may be linked to the histologic grade or proliferative activities.

OBJECTIVE

To study the expression of cyclin A and cyclin B1 proteins in astrocytomas and correlate the labeling indices (LIs) of cyclin A and cyclin B1 with histologic grade and Ki-67 LI.

DESIGN

The surgical biopsy specimens from 65 adults with astrocytomas were reviewed and divided into grades based on the World Health Organization system. The paraffin sections were immunostained using primary antibodies against Ki-67, cyclin A, and cyclin B1. The LIs of these astrocytomas for the 3 different antibodies were determined by computerized image analysis.

RESULTS

The cyclin A LI showed good correlation with astrocytoma grade and Ki-67 LI. Both the nuclear and cytoplasmic cyclin B LIs correlated well with the tumor grade but showed poor correlation with Ki-67 LI.

CONCLUSIONS

This study suggests that although both cyclin A and B protein expression are related to the grade of malignancy in astrocytomas, cyclin A levels more generally reflect the proliferative state of these tumors. We also provide indirect evidence that cyclin B1 is associated with the aberrant progression through the G2-M phase checkpoint in astrocytomas.

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.

In vivo determination of 5-bromo-2'-deoxyuridine incorporation into DNA tumor tissue by a new 32P-postlabelling thin-layer chromatographic method

The halopyrimidine 5-bromo-2'-deoxyuridine (BUDR) can serve as one of many indicators of tumor malignity, complementary to histologic grade. We have developed a thin-layer chromatographic (TLC) technique that can assess tumor DNA base composition and analogue (BUDR) incorporation which vies with immunochemistry for BUDR. This requires post-labeling DNA by nick-translation and radioactive 5'-phosphorylation of representative 32P-alpha-dNMPs (deoxynucleotide monophosphates). Subsequent 3'-monophosphate digest exchanges a radioactive 32PO4 for the neighboring cold nucleotide. Separation in two dimensional PEI-cellulose TLC is carried out in acetic acid, (NH4)2SO4, and (NH4)HSO4. TLC of dNMPs was applied to control HeLa DNA, and HeLa cells receiving BUDR. BUDR is detected in 10(6) HeLa cells after 12-72 h incubations. Findings in HeLa DNA demonstrate normal TLC retention factors for all 32P-dNMPs. Two dimensional R(F) (x,y axes in cm) demonstrate: dAMP=1.4, 9.4; dCMP=10.0, 13.5; dGMP=4.6, 4.4; dTMP=9.0, 7.4; and BUDRMP 6.4, 6.6. This technique quantifies BUDR--which parallels tumor S phase, and serves as an indicator of labelling index (LI).

Recognition and management of gliomas

Gliomas are the most frequent primary brain tumours. They include astrocytic gliomas, oligodendrocytic gliomas, ependymomas and gliomas with mixed cell populations. Each glioma type consists of both low-grade and malignant atypical varieties. The low-grade tumours occur predominantly in children and young adults, and the malignant forms in older people. The presenting symptoms are epileptic seizures, headache and mental confusion. Focal neurological symptoms and findings, such as hemiparesis, are mostly associated with the malignant forms. Magnetic resonance imaging (MRI) scan of the brain with and without gadolinium contrast demonstrates the tumour. However, stereotactic biopsy or surgical resection is necessary to obtain the correct pathological diagnosis, except for diffuse pontine astrocytomas, which have an unmistakeable imaging appearance and for which biopsy has substantial risks. Treatment depends on the pathological diagnosis. Complete surgical resection may be curative for low-grade tumours. Postoperative radiotherapy is recommended for partially resected tumours. Most malignant gliomas require aggressive combination therapy with radiotherapy and chemotherapy after maximal surgery. The standard initial regimens are nitrosourea-based chemotherapies, such as carmustine alone, a combination of procarbazine, lomustine and vincristine, or a combination of thioguanine, procarbazine, lomustine and hydroxycarbamide (hydroxyurea). Unfortunately, the prognosis of malignant gliomas is generally poor despite aggressive treatment, because of their infiltrative nature and high relapse rate.

The in vivo metabolic pattern of low-grade brain gliomas: a positron emission tomographic study using 18F-fluorodeoxyglucose and 11C-L-methylmethionine

OBJECTIVE

The object of the present study was to identify metabolic differences between low-grade astrocytomas and oligodendrogliomas and to improve their diagnosis and noninvasive assessment, because both types of tumors look very similar from the point of view of clinical and radiological data (as assessed by computed tomography and magnetic resonance imaging).

METHODS

Before any aggressive treatment, 22 patients with primary low-grade gliomas (astrocytomas in 12 patients and oligodendrogliomas in 10) were investigated with positron emission tomography for both glucose metabolism (18F-fluorodeoxyglucose) and amino acid uptake (11C-L-methylmethionine). An original software that allows a full metabolic analysis of the tumor region of interest (defined from the T1-weighted magnetic resonance image) and compares tumor tissue uptake tracer concentrations with average healthy tissue values has been implemented for data processing. Heterogeneity of each individual tumor has been taken into account and was expressed in histograms, which provided data about the mean and also extreme and intermediate values of tracer concentrations and the way these values are distributed among the full tumor mass.

RESULTS

It has been shown that both tumor types exhibit a glucose hypometabolism (slightly more pronounced with astrocytomas), whereas they strongly differ in methionine uptake, which is high in all oligodendrogliomas and either decreased, normal, or moderately increased in astrocytomas. This latter metabolic difference between both tumor populations may be partially explained by their different cell densities.

CONCLUSION

This study suggests that despite similar radiological and clinical presentations, these two kinds of low-grade gliomas are metabolically different and could therefore have specific responses to different therapies. Moreover, their in vivo metabolic follow-up with positron emission tomography should rely on different parameters, depending on their histological type; methionine uptake may be more relevant than glucose metabolism in the follow-up of oligodendrogliomas.

The level of MnSOD is directly correlated with grade of brain tumours of neuroepithelial origin

The oxy-radical scavenger enzyme manganese superoxide dismutase (MnSOD) may act in the capacity of a tumour-suppressor gene. To address the issue of its role in tumour transformation and progression in vivo, we evaluated the content of this enzyme in 33 brain tumours of neuroepithelial origin with different degrees of differentiation (WHO grade II-IV) by means of Western blot and immunohistology. Our results show that immunoreactive MnSOD increases in a direct relationship with tumour grade and is therefore inversely correlated with differentiation. The increase in induced at a pretranscriptional level and is apparently specific to brain tumours of neuroepithelial origin. Approximately 30% of grade IV tumours display low levels of MnSOD content, and preoperative radiotherapy and brachytherapy result in low amounts of enzyme. Based upon these observations, we suggest that MnSOD cannot be considered a classical tumour-suppressor gene.

Bromodeoxyuridine labeling index in glioblastoma multiforme: relation to radiation response, age, and survival

PURPOSE

Various measures of the rate of tumor cell proliferation have been found to predict survival in patients with intracerebral gliomas. We correlated the bromodeoxyuridine labeling index (BrdUrd LI) with the response to radiation therapy, survival, and known prognostic factors in a series of patients with glioblastoma multiforme (GM) to test its utility as a prognostic factor.

METHODS AND MATERIALS

The BrdUrd LI was determined in 200 newly diagnosed intracranial GMs. Age and sex were known for all patients. The response to radiation therapy was determined in 116 patients by comparing neuroimaging studies obtained before and after external beam radiation therapy. Survival was analyzed in 64 patients who were treated according to two consecutive prospective clinical protocols.

RESULTS

The median BrdUrd LI was 6.5% (mean, 7.2%; range, 1.1-25.4%). The BrdUrd LI did not correlate significantly with age, sex, radiation response, or survival. Age and Karnofsky performance score were independent prognostic factors in our cohort.

CONCLUSION

The proliferative rate as measured by BrdUrd LI was not a prognostic factor in our GM cohort. The BrdUrd LI did not correlate significantly with known prognostic factors in GM. There was no significant relationship between BrdUrd LI and radiation response.

Microvessel density is a prognostic indicator for patients with astroglial brain tumors

BACKGROUND

Microvessel density in tumors, a measure of angiogenesis, has been shown to be a prognostic indicator that correlates with an increased risk of metastasis in various epithelial cancers and with overall and relapse free survival in patients with breast cancer. Astrocytic brain tumors, particularly malignant astrocytomas, are recognized to be highly vascular tumors with potent angiogenic activity. However, the prognostic significance of microvessel density in these tumors is not known.

METHODS

Sections from formalin fixed paraffin embedded tumor tissue from 93 unselected adult patients with supratentorial astrocytic brain tumors were immunostained for factor VIII-related antigen in order to highlight microvessel endothelial cells. Microvessels were counted at 200x and 400x magnification. Microvessel density was graded as 1+ to 4+ on 1 low power field, without knowledge of clinical outcome. Microvessel count and microvessel grade were correlated with postoperative survival using the Cox proportional hazards regression model. The prognostic significance of microvessel count and grade were also compared with established prognostic indicators, including patient age, Karnofsky performance status, and tumor histology using multivariate analyses.

RESULTS

Both microvessel grade and microvessel count correlated significantly with postoperative survival by univariate analysis in both previously untreated and treated patients. Patients with tumors containing a microvessel Grade of 3+ or 4+ had significantly shorter survival time than patients with a microvessel Grade of 1+ or 2+ (P = 0.0022). Likewise, patients with microvessel counts of 70 or greater had significantly shorter survival than those with microvessel counts of fewer than 70 (P = 0.041). Patient age, Karnofsky performance status, tumor histology, and extent of resection were also correlated with survival by univariate analysis. Microvessel count was further shown to be an independent prognostic indicator by multivariate analyses. There were correlations between microvessel density and patient age and between microvessel density and astrocytic tumor grade.

CONCLUSIONS

These findings support the importance of microvessel density as a prognostic indicator of postoperative survival of patients with astroglial brain tumors. Regional tumor heterogeneity may limit the use of these techniques for routine pathologic examination.

Prognostic significance of bromodeoxyuridine labeling in primary and recurrent glioblastoma multiforme

To evaluate the prognostic significance of bromodeoxyuridine (BUdR) labeling index (LI) and to estimate tumor proliferative potential, BUdR LI was examined in 98 patients having a primary diagnosis of glioblastoma multiforme (GBM); 55 underwent infusion of 200 mg/m2 of BUdR at the time of the primary resection and 49 underwent infusion at the time of the second resection. The tumors of six patients were labeled at both operations. The tumor specimens were stained with hematoxylin and eosin for histopathology and by immunohistochemical methods to determine the ratio of labeled to unlabeled cells, i.e., BUdR LI. The median BUdR LIs for the primary and recurrent GBM were significantly different at 6.8 and 2.6%, respectively (P < 0.0001). However, there was no significant association between BUdR LI at the first or second operation and survival (log rank, P = 0.12; Cox regression analysis, P = 0.91; log rank, P = 0.55; Cox regression analysis, P = 0.17, respectively). Patients who underwent a second operation within 10 months of the first operation had a lower BUdR LI than did patients with a longer interval between procedures (P = 0.078; Spearman rank correlation, 0.26). The aggressive biological behavior of GBM is dependent on complex cellular kinetics, not simply on the number of cells within the S phase of the cell cycle. Caution should be used when determining prognosis with BUdR LI in GBM.

Prognostic significance of Ki-67 proliferation index in supratentorial fibrillary astrocytic neoplasms

Histological grading of fibrillary astrocytic neoplasms has proved to be a valuable prognostic tool, but potentially could benefit from more objective data, such as estimates of proliferative rate. The authors have investigated the prognostic utility of quantitative Ki-67 immunoreactivity in a prospective survival analysis of 36 adult patients with astrocytoma, anaplastic astrocytoma, or glioblastoma multiforme diagnosed between 1987 and 1992. A digital image analyzer was used to assay proliferation indices (PIs) in surgical biopsy specimens obtained at first diagnosis (32 of 36) or at a second biopsy of histologically unchanged high-grade disease (4 of 36). A Ki-67 PI of > or = 7.5% was associated with higher histological grade and poorer survival, and the Ki-67 PI was more significantly related to survival (P < 0.001) than histological grade as determined by a modified Ringertz grading system (P = 0.002). Survival analysis within histological grades suggested that astrocytoma patients with PI > or = 3% may be at increased risk for shorter survival than those with PI < 3%.

The application of 5-bromodeoxyuridine in the management of CNS tumors

A variety of clinical reports have described the application of the bromodeoxyuridine labeling index as an adjunct to conventional pathological examination of CNS tumors. This index has proven useful in predicting the clinical outcome associated with many such tumors. Furthermore, because of its efficacy as a radiosensitizing agent, bromodeoxyuridine (and the closely related iododeoxyuridine) has been used in combination with radiation therapy for malignant glial neoplasms, with some encouraging results. Although most studies suggest that bromodeoxyuridine is safe, there is evidence that this compound does have potential side-effects, including the observation that it is a mutagen and carcinogen in some experimental systems. A number of new alternative approaches for predicting the clinical outcome of CNS tumors has been developed based on an increased understanding of their molecular biology. However, until such approaches are better characterized, the clinical application of bromodeoxyuridine will continue to play an important role in predicting the clinical behavior of many CNS tumors.

Ki-67 immunoreactivity in human central nervous system tumors: a study with MIB 1 monoclonal antibody on archival material

Paraffin-embedded surgical specimens from 136 primary human central nervous system (CNS) tumors, including 50 meningiomas, 24 astrocytomas, 26 anaplastic astrocytomas, 9 glioblastomas, 8 oligodendrogliomas, 4 ependymomas, 1 anaplastic ependymoma, 2 subependymomas, 9 medulloblastomas, and 3 paragangliomas, were immunostained, following microwave processing, using a streptavidin/peroxidase method and the MIB 1 monoclonal antibody (mAb) against the Ki-67 antigen. The following mean Ki-67 labeling index (LI) values +/- SD were found: meningiomas, 2.47 +/- 1.83; astrocytomas, 2.03 +/- 2.03; anaplastic astrocytomas, 12.80 +/- 6.29; glioblastomas, 14.57 +/- 6.77; oligodendrogliomas, 5.06 +/- 4.78; ependymomas, 2.63 +/- 2.58; anaplastic ependymoma, 6.89; subependymomas, 1.79 +/- 1.54; medulloblastomas, 18.77 +/- 9.65; and paragangliomas, 2.19 +/- 2.51. Our findings indicate that while malignant CNS tumors always exhibited high Ki-67 LI values, and benign CNS tumors generally displayed lower values, increased immunoreactivity for Ki-67 epitopes (Ki-67 LI higher than 4) was noted in a number of meningiomas, astrocytomas, ependymomas, oligodendrogliomas and paragangliomas, contrasting with their benign histological features. Further investigations of the Ki-67 immunoreactivity in CNS tumors and systematic correlation with the postoperative follow-up of patients are necessary to determine the value of Ki-67 LI in predicting the biological behavior of CNS neoplasms.

Proliferative potential and prognostic evaluation of low-grade astrocytomas

Despite their histological similarity, low-grade astrocytomas vary widely in their clinical behavior. To elucidate this variable behavior, we measured the proliferative potential of 69 primary and 18 recurrent low-grade astrocytomas and correlated the results with the clinical characteristics and outcome. Each patient received an intravenous infusion of bromodeoxyuridine (BUdR); BUdR-labeled nuclei in excised tumor specimens were identified by immunoperoxidase staining. The BUdR labeling index (LI), or S-phase fraction, ranged from < 1 to 9.3%; the LI was < 1% in 64 (74%) patients and > or = 1% in 23 patients (26%). The LI did not appear to be associated with age, sex, tumor location, or whether the tumor was primary or recurrent. A Cox proportional-hazards analysis of the influence of the LI and other variables (age, sex, tumor location, extent of surgery, primary versus recurrent tumor) on survival showed that the LI and extent of surgery (total resection, subtotal resection, biopsy) were significant in predicting both survival and progression-free survival for all patients and for patients with primary tumors. The LI was also significant in predicting progression-free survival for patients with recurrent tumors. The correlation between the BUdR LI and both survival and time to recurrence suggests that the outcome of low-grade astrocytomas varies according to the proliferative potential. The growth rate of these histologically similar tumors should be assessed individually in order to select specific treatment.

Cell kinetic classification of tumors of the nervous system by DNA precursor labeling in vitro

We studied 142 excisional or needle biopsy specimens of nervous system tumors with tritiated thymidine or 5'-bromodeoxyuridine (BrdUrd). Either precursor gave similar results. A labeling index (LI), expressed as a percentage and representing the S-phase fraction, was measured by a microscopic count from stained sections. The in vitro method ranked mean and median LIs of different neoplasms similarly to reported results from the in vivo administration of BrdUrd and reflected clinical aggressiveness of various tumor types. Gliosis, myxopapillary ependymomas, benign meningiomas, neurilemmomas, and pituitary adenomas consistently showed LIs less than 1%. The LI of a cerebellar Lhermitte-Duclos gangliocytoma was zero, indicating the virtual absence of proliferation. Mean LIs and standard deviations of other tumors were as follows: anaplastic astrocytomas, 3.07% +/- 2.98%; glioblastoma multiforme, 6.15% +/- 5.61%; non-Hodgkin's lymphoma, 12% +/- 9.5%; and metastatic neoplasms, 15% +/- 8.5%. The survival rate of patients with astrocytic tumors was inversely proportional to the LI. We conclude that the in vitro method is a practical alternative to in vivo BrdUrd administration for measurement of S-phase cells in tumors of the nervous system that gives prognostically useful information. Combination of BrdUrd LI with growth fraction measurement by monoclonal antibodies could offer new insights into brain tumor cell kinetics.

Detection of proliferating cell nuclear antigen in gliomas and adjacent resection margins

We describe a technique for estimating the number of proliferating cells in gliomas and adjacent resection cavities after tumor removal. Proliferating cell nuclear antigen (PCNA) is a nuclear protein associated with the cell cycle. Anti-PCNA antibody staining provides a semiquantitative estimate of the number of proliferating cells found in fixed tissue embedded in paraffin. The extent of the staining of tumor cells of glioblastoma multiforme, anaplastic astrocytomas, low-grade gliomas, and other lesions of the brain with anti-PCNA antibody is correlated with the histological diagnosis. In addition, the labeling of the margins after resection of gliomas and other lesions with anti-PCNA antibody is also associated with the histological diagnosis of the lesion. This technique may be useful in estimating the "biological" extent of resection and in predicting the recurrence patterns of gliomas.

Significance of proliferating cell nuclear antigen index in predicting pituitary adenoma recurrence

The recurrence rate of pituitary adenomas has been reported to be as high as 10% to 35% despite their generally benign nature. A monoclonal antibody directed against proliferating cell nuclear antigen (PCNA) was used to investigate whether the proliferative index might help to predict adenoma recurrence. This antigen is a nuclear protein identified as the auxiliary protein of deoxyribonucleic acid polymerase delta, and its gene expression correlates with cell proliferation. The authors studied 30 patients with recurrent pituitary adenomas, 32 with nonrecurrent adenomas, and seven normal pituitary tissue samples. The mean interval to recurrence ( +/- standard error of the mean) was 5.3 +/- 0.7 years. The age- and sex-matched nonrecurrent group had a mean follow-up period of 6.6 +/- 0.3 years without clinical recurrence. Mean percentages of PCNA-positive tumor nuclei in both the initial and the second surgical specimens of the recurrent adenomas (13.45% +/- 3.02% and 19.56% +/- 3.66%, respectively) were significantly higher than that of the nonrecurrent group (2.49% +/- 1.21%). In addition, recurrent tumors had a higher PCNA index than the initial tumors in the same patients. Normal anterior pituitary gland tissue had a significantly lower mean PCNA index (0.12% +/- 0.11%) than either patient group. Stepwise multivariate regression analysis indicated that factors which collectively correlated significantly with recurrence were: high PCNA index, large tumor size, extrasellar extension, and incomplete surgical excision. The PCNA nuclear count was not associated with age, sex, or hormone hypersecretion, but was higher in macro- than in microadenomas, in tumors with extrasellar extension, and in those incompletely excised. A higher PCNA index also correlated with a shorter disease-free interval. The authors conclude that evaluation of the PCNA index assists in predicting the likelihood of pituitary adenoma recurrence.

Use of [18F]fluorodeoxyglucose positron emission tomography in patients with primary malignant brain tumors

In patients with malignant gliomas, [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) may discriminate tumor progression from radionecrosis. We evaluated data from 50 patients undergoing FDG-PET for suspicion of tumor progression. Forty-nine were treated with surgery, 48 with radiotherapy, and 37 with chemotherapy. Twenty-one had intensive radiotherapy with either three daily treatments in two 5-day periods and intravenous carboplatin (17) or interstitial brachytherapy or stereotactic radiotherapy. Twenty underwent surgery after magnetic resonance imaging/FDG-PET; 9 demonstrated increased uptake of FDG and evidence of tumor, whereas 6 had decreased uptake and no evidence of tumor. In 5 patients, there was no correlation (all had intensive radiotherapy). In 17 patients who received bromodeoxyuridine intravenously just before surgery, the bromodeoxyuridine labeling index corresponded to the histological appearance in all but 2 patients (both had received intensive radiotherapy). In 30 patients without surgery, decreased uptake of FDG suggested prolonged survival; increased uptake of FDG did not predict survival. Eight of 10 with intensive radiotherapy had decreased label uptake. We conclude FDG-PET for evaluation of patients with possible recurrent tumors requires more study. In patients with intensive radiotherapy, FDG-PET results cannot be correlated accurately with tumor progression.

Proliferating cell nuclear antigen (PCNA): expression in samples of human astrocytic gliomas

In this retrospective study, 55 astrocytic tumours were stained with monoclonal antibody PC10 which recognizes the proliferating cell nuclear antigen (PCNA) in formalin fixed, paraffin-wax embedded sections. All the cases were graded using the Daumas-Duport system and the PCNA labelling indices (LIs) were correlated with tumour grades. Mean PCNA LI was 4.1% in the grade II, 8.1% in the grade III and 26.1% in the grade IV group. Six juvenile and cerebellar (grade I) astrocytomas had a mean PCNA LI of 5.6%. In general PCNA LI increased with tumour grade, but there was considerable variation of LIs especially in grade IV tumours which often had very high PCNA LIs (up to 72.7%). PC10 may be a useful complementary technique in surgical neuropathology, but the significance of the high LIs, seen in a proportion of glioblastomas, needs to be further determined.

Biology and treatment of gliomas

This review discusses some of the recent advances in glioma research and treatment. Our understanding of the characteristics of these tumors has been strengthened by the application of molecular biologic and genetic techniques to pathologic grading and therapy outcome. Newer attempts to correlate imaging modalities to pathologic grading are also discussed. It is anticipated that these developments will strengthen our ability to design improved treatment strategies, an essential goal inasmuch as current treatment schemes have limited benefit. More work needs to be done to understand the biology of these tumors especially the complex interactions of their cytokine expression, multiplicity of genetic abnormalities, and their local environment. Only then will be able to develop improved therapeutic interventions.