Flow cytometric DNA and nuclear antigen content in astrocytic neoplasms

Cellular DNA content parameters as prognostic indicators in human astrocytomas

OBJECTIVE

Clinical parameters such as grade, size and/or location of the tumor are good predictors of outcome in patients with astrocytoma. The objective of this study was to determine whether DNA content parameters have a prognostic significance for this group of tumors.

METHODS

Following optimization and validation of methodology for evaluating cellular DNA content parameters (CDCP), tumor DNA ploidy and percent S phase fraction (SPF) were determined from 64 patients using formalin fixed, paraffin embedded specimens (mean coefficient of variation=4.94) obtained over a 10-year period. Median survival times correlated with grade (I/II=1154 vs. III/IV=483days, P=0.0317). Fifty-five percent of the specimens contained DNA aneuploid (DNA-A) components (average SPF=18.3%) and 45% were DNA diploid (DNA-D) (average SPF=9.6%). Survival did not correlate with overall differences in DNA ploidy (DNA-D=181 vs. DNA-A=206days, P=0.6314) when treated and untreated tumors were analyzed. However, a trend for prolonged median survival was observed in patients whose tumors were untreated with respect to cytotoxic therapy based on DNA ploidy status (DNA-D=275 vs. DNA-A=15days, P=0.3408). Survival for all patients did not correlate with median SPF (<13.5% av.=121 vs. >13.5% av.=154days, P=0.6534).

CONCLUSION

DNA content parameters may correlate with the natural history and treatment outcome of newly diagnosed untreated patients with astrocytomas.

Gene expression profiling of gliomas strongly predicts survival

In current clinical practice, histology-based grading of diffuse infiltrative gliomas is the best predictor of patient survival time. Yet histology provides little insight into the underlying biology of gliomas and is limited in its ability to identify and guide new molecularly targeted therapies. We have performed large-scale gene expression analysis using the Affymetrix HG U133 oligonucleotide arrays on 85 diffuse infiltrating gliomas of all histologic types to assess whether a gene expression-based, histology-independent classifier is predictive of survival and to determine whether gene expression signatures provide insight into the biology of gliomas. We found that gene expression-based grouping of tumors is a more powerful survival predictor than histologic grade or age. The poor prognosis samples could be grouped into three different poor prognosis groups, each with distinct molecular signatures. We further describe a list of 44 genes whose expression patterns reliably classify gliomas into previously unrecognized biological and prognostic groups: these genes are outstanding candidates for use in histology-independent classification of high-grade gliomas. The ability of the large scale and 44 gene set expression signatures to group tumors into strong survival groups was validated with an additional external and independent data set from another institution composed of 50 additional gliomas. This demonstrates that large-scale gene expression analysis and subset analysis of gliomas reveals unrecognized heterogeneity of tumors and is efficient at selecting prognosis-related gene expression differences which are able to be applied across institutions.

Flow-cytometric DNA analysis of intracranial tumors in children

The objective of this study was to investigate flow-cytometric DNA values of pediatric intracranial tumors, and to establish DNA analysis as a potential prognostic parameter. Twenty-nine brain tumor specimens from 26 pediatric patients were cryo-preserved within a 3-year period. The DNA content was measured by flow cytometry. Six of the tumor specimens had aneuploid DNA patterns. The median of the proliferation index was lower in the survivor group compared with the non-survivor group (36.4% and 47.5%, respectively). Ten of the 26 patients are still alive, eight were lost to follow up, and eight died. Flow-cytometric DNA analysis may be a helpful tool for examining brain tumors in children. The small size of this study could not establish flow cytometry as a definite prognostic factor, but further prospective multicenter studies will evaluate the prognostic significance of flow-cytometric DNA analysis.

Prognostic significance of DNA ploidy in childhood astrocytomas

The ability to divide subsets of children with astrocytoma into prognostic groups is limited because only a few clinical and pathologic variables are available. This study evaluated DNA ploidy as a potential prognostic factor in 30 children with diagnosed gliomas and examined the correlation of flow cytometric analysis to other parameters such as sex, age at diagnosis, histologic grading, localization of tumor, and completeness of surgical resection. Seventeen children with low-grade glioma and 13 with high-grade glioma were retrospectively reviewed; mean age of the patients was 8.2 years, and mean follow-up of the population was 7.6 years. The tumor was localized to the cerebrum in 19 patients, the cerebellum in 7 patients, the brain stem in 3 patients, and the spine in 1 patient. Fourteen patients underwent complete excision and 16 patients underwent partial excision. DNA diploidy was demonstrated in 21 patients and aneuploidy in 9 patients. Twenty children had no evidence of disease and 10 died of disease. Of the patients with diploid tumors, 81% survived, compared to only 33% survival among patients with aneuploid tumors (p < .011). By Cox regression analysis with age, gender, type of excision, grade, location of tumor, and ploidy as independent variables, ploidy was a statistically significant predictor of survival (p = .043). This investigation provides further evidence that flow cytometry may have prognostic value in children with gliomas. Thus, a larger number of tumors can be studied to extend and validate these observations.

Supratentorial ependymomas in adult patients

OBJECTIVE

Ependymomas arise from different areas in the neuraxis and have variable outcomes that depend on tumor location and patient age at the time of presentation. The predictive value of histology for these tumors is unresolved. We report a series of adult patients with supratentorial ependymomas to characterize the roles of surgery, histology, ploidy, and proliferation index in tumor control.

METHODS

Fourteen of the 23 supratentorial ependymomas were in the region of the third ventricle and the remainder were located in the hemispheres. Resections were gross total in 12 patients, subtotal in 8, and biopsy in 3. A single pathologist reviewed all slides and quantitated the deoxyribonucleic acid. The mean follow-up duration was 95 months (+/-75 mo).

RESULTS

All of the malignant ependymomas were hemispheric (n = 4). Mortality occurred only in patients with third ventricular tumors; two patients died as a result of surgical complications and three as a result of tumor progression. Kaplan-Meier estimates of 5- and 10-year survival rates were 100% for hemispheric and 72.5% for third ventricular tumors (62.5% including the two perioperative deaths). The median time to recurrence was 53 months, with a 10-year progression-free survival rate of 27%. Univariate analysis revealed that recurrence was associated with malignant histology, including mitoses, cellularity, and aneuploidy. For nonmalignant ependymomas, recurrence was associated with subtotal resection and metastases. S-phase fraction did not correlate with recurrence. Only malignant histology correlated with recurrence on multivariate analysis.

CONCLUSION

Although the numbers are too small to draw any definite conclusions, treatment of ependymomas that arise in the supratentorial compartment in adult patients results in excellent outcomes despite frequent recurrences. Association with the third ventricle and metastases seem to have a negative impact on survival, whereas malignant histology, subtotal resection, and metastases may be predictors of recurrence.

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content in patients with renal cell carcinoma

BACKGROUND

Although tumor stage and grade are important prognostic parameters for patients with renal cell carcinoma, postnephrectomy survival is often difficult to predict. Therefore identifying patients at high risk for disease progression is critical. Using two-color flow cytometry, DNA and proliferation-associated nuclear antigen p105 contents were measured simultaneously in 75 patients with renal cell carcinomas and the ability of these results to predict the survival was assessed.

METHODS

Flow cytometric study of the proliferation-associated nuclear antigen p105 was done on cancer cell suspensions from 75 patients with renal cell carcinomas. By setting the cutoff line at the level between the brighter and the dimmer subpopulations in the diploid G0G1 region, the p105-labeling rate was calculated by the p-105DNA dual fluorescence analysis.

RESULTS

The mean p105-labeling rate was 66.8% (median: 67.6%; range: 33.9-93%). The 5-year survival rate of patients with high p105-labeling tumors was significantly lower than that of patients with low labeling tumors (P < 0.05). The following factors were examined univariantly as prognostic factors: Robson's stage, DNA ploidy pattern, grade, and p105-labeling rate. All of these factors except for DNA ploidy pattern were prognostic. The Cox multivariate regression analysis was performed with the three statistically significant variables. Accordingly, these three factors were significantly associated with survival rate and were found to be independent prognostic factors.

CONCLUSIONS

The measurement of p105 may provide useful information for predicting prognosis of patients with renal cell carcinoma.

Nuclear morphometry and DNA densitometry of human gliomas by image analysis

In 48 patients with gliomas in whom complete clinical follow-up was obtained, DNA ploidy was evaluated by using formalin-fixed paraffin-embedded tissues and by means of image analysis. The mean DNA indices, determined by averaging DNA indices of all tumor cells in a tumor, were mainly affected by mean DNA indices of the nuclei of SG2M phase tumor cell (including S phase and G2M phase cells) (SG2M DNA indices) and that mean DNA indices correlated with the SG2M phase fraction. The SG2M DNA indices and the percentage of tumor cells with S phase and G2M phase were higher in high grade gliomas including anaplastic glioma and glioblastoma multiforme than in low grade gliomas. Patients with G2M-hypertetraploid tumors demonstrated a shorter time to tumor progression than those with G2M-tetraploid in high grade glioma. Morphometrically, the nuclei of SG2M phase glioma cells were larger and more deformity than those of G0G1 phase (including G0 phase and G1 phase cells) cells. The G2M-hypertetraploid tumors were highly malignant and demonstrated large nuclei, greater nuclear deformity, and a higher proliferative potential. The G2M-tetraploid gliomas demonstrated a shorter time to tumor progression in cases whose the SG2M fraction was large. In contrast, G2M-hypotetraploid gliomas revealed an insignificant trend towards a longer time to tumor progression than those associated with tetraploid and hypertetraploid gliomas. We emphasize herein the prognostic importance of the SG2M phase cell, as well as other proliferation indices.

Use of a multiparametric panel to target subpopulations in a heterogeneous solid tumor model for improved analytical accuracy

The exclusion of non-tumor and dead cells from the analysis of live tumor cells can significantly improve the accuracy of prognostic indicators such as proliferative and DNA indexes. To target live breast tumor cells in a heterogeneous breast tumor model, we have designed a panel consisting of the DNA-specific dye DAPI and epithelial tissue-specific (cytokeratin), tumor-associated (MC5), proliferation-associated (proliferating cell nuclear antigen), and viability-associated (tubulin) markers. The breast tumor model consisted of a mixture of equal numbers of live and dead MDA-MB-175-VII (breast tumor) cells, live CEM (leukemic) cells, and live peripheral blood mononuclear cells. Targeting the live MDA cells in the mixture by gating on tubulin, cytokeratin, and MC5 resulted in a sevenfold increase in PCNA positivity (from 3% ungated to 22.3%), a 60% decrease in the %S-phase fraction (from 37.2% ungated to 15%), and elimination of extraneous hypodiploid and diploid components, enriching the tetraploid MDAs. These results are consistent with those obtained from unmixed live MDA cells. The combined utilization of this panel and "cumulative" electronic gating of the targeted population increases the number of relevant parameters that can be analyzed per sample and the accuracy of the resultant data.

Relationship between DNA ploidy level and tumor sociology behavior in 12 nervous cell lines

Cell population sociology was studied in two medulloblastomas and 10 astrocytic human tumor cell lines by means of the characterization of the structure of neoplastic cell colonies growing on histological slides. This was carried out via digital cell image analysis of Feulgen-stained nuclei, to which the Delaunay triangulation and Voronoi paving mathematical techniques were applied. Such assessments were compared to the DNA polidy level (assessed by means of DNA histogram typing). The results show that the cell colony architecture characteristics differed markedly according to whether the cell lines were euploid (diploid or tetraploid) or aneuploid (hyperdiploid, triploid, hypertriploid, or polymorphic). In fact, the cell colonies from the euploid cell nuclei populations were larger and more dense than those from the aneuploid ones. Furthermore, for an identical period of culture, the cell lines from high-grade malignant astrocytic tumors (glioblastomas) exhibited cell colonies that were larger and more dense than those in cell lines from low-grade astrocytic tumors (astrocytomas). In each of these two groups, the diploid cell nuclei populations exhibited cell colonies larger and more dense than the nondiploid colonies. The present methodology is now being applied in vivo to histological sections of surgically removed human brain tumors in order to distinguish between high-risk clinical subgroups and medium-risk subgroups in clearly circumscribed histopathological groups.

Management of supratentorial low-grade gliomas

Low-grade gliomas are a clinically, radiographically, and pathologically diverse group of central nervous system neoplasms. Treatment decisions are based primarily on histologic tumor type and patient age. Pilocytic astrocytomas tend to occur in younger patients, are circumscribed, and amenable to cure with gross total resection. There is no role for the routine use of postoperative radiotherapy in these patients. In contrast, infiltrative tumors, including ordinary (nonpilocytic) astrocytomas, mixed oligoastrocytomas, and oligodendrogliomas occur in middle-aged patients and are generally not curable, even with gross total resection. Postoperative radiotherapy of these infiltrative tumors appears to improve survival, particularly in adults. Several ongoing clinical trials are addressing two issues: Observation vs radiotherapy and low-dose vs high-dose radiotherapy in patients with ordinary astrocytomas, oligoastrocytomas, and mixed oligoastrocytomas.

Relationship between proliferative activity and ploidy level in a series of 530 human brain tumors, including astrocytomas, meningiomas, schwannomas, and metastases

By identifying six DNA histogram types (diploid, hyperdiploid, triploid, hypertriploid, tetraploid, and polymorphic) in a series of 206 astrocytic tumors, we showed recently that patients with hypertriploid astrocytic tumors have a better possibility of survival than patients with other DNA histogram-type related tumors. In the present work DNA histogram type and proliferation index (S-phase fraction) are characterized in a series of 530 adult tumors from the central and peripheral nervous systems. Of these 530 tumors, there were 79 nerve sheath tumors, 181 meningiomas, 221 astrocytic tumors, and 49 metastases. Analysis was performed by means of digital cell image examination of Feulgen-stained nuclei from formalin-fixed, paraffin-embedded tumors. The data reveal that there was a majority of diploid tumors (66%) in the primary tumor group (nerve sheath tumors, meningiomas, and astrocytic tumors), while aneuploid tumors were in a marked majority (90%) in the secondary (metastatic) brain tumor group, with a predominance (47%) of the polymorphic tumor type. Independently of tumor histopathologic group, the hypertriploid-type tumors proliferated less actively than the five other types. Such a feature might partly explain the better prognosis associated with hypertriploid astrocytic tumors as compared with what occurs with respect to the other DNA histogram-type related tumors.

Histopathologic grading and DNA ploidy in relation to survival among 206 adult astrocytic tumor patients

BACKGROUND

The authors studied the benefit of performing histopathologic grading and DNA ploidy characterization with respect to patient survival in a series of 206 astrocytomas (AST) for which they obtained 134 complete clinical follow-ups.

METHODS

The material analyzed came from archival material, i.e., formalin-fixed paraffin-embedded tissues. DNA ploidy was assessed by means of a cell image processor computing the integrated optical density (IOD) on Feulgen-stained nuclei.

RESULTS

Results showed that histopathologic diagnosis in three grades, i.e., AST, anaplastic astrocytoma (ANA), and glioblastoma multiforme (GBM), had a significant prognostic value. Patients with AST showed a mean survival time (between histopathologic diagnosis and death) of more than 36 +/- 6 months (AST versus ANA or GBM) (P less than 0.001). Patients with ANA and GBM showed a mean survival time of 15 +/- 2 and 10 +/- 1 months, respectively, (ANA versus GBM) (P less than 0.05). Patient age strongly correlated with survival. Patients younger than 40 years of age had a mean survival time of 20 +/- 4 months. Patients between 41 and 60 years of age had a mean survival time of 12 +/- 2 months, and patients older than 60 years of age had a mean survival time of 11 +/- 1 months.

CONCLUSIONS

Considering DNA ploidy characterization, the authors noticed that aneuploid ANA (DNA index [DI] more than 1.30) were associated with a significantly higher mean patient survival time compared with that associated with euploid ANA. In contrast, the authors did not find this in either of the groups with AST and GBM. Recognizing six DNA histogram types (diploid, triploid, tetraploid, hyperdiploid, hypertriploid, and polymorphic), the authors observed that hypertriploid tumors were associated with greater patient survival compared with what happened in the cases of the five other DNA histogram types. This was true with respect to the three AST histopathologic types. Thus, DNA ploidy determination seemed helpful in characterizing aggressiveness in adult AST.

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content in advanced gastric cancers

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 was done on cancer cell suspensions from 114 advanced gastric cancers and correlated with clinical behavior. DNA diploidy was observed in 45 (39.5%) and aneuploidy in 69 (60.5%) cases. By setting the cutoff line at the level used in a negative control study without primary antibody in the same sample, the p105-labeling rate was calculated by the p105-DNA dual fluorescence analysis. The mean p105-labeling rate was 37.7% (range, 9.3% to 79.0%). The p105-labeling rates were significantly higher (P less than 0.05) for aneuploid DNA, liver metastasis, vascular invasion, and histologically well-differentiated tumors. The 5-year survival rate of patients with high p105-labeling tumors (p105-labeling rate, greater than 30%) was significantly poorer (P less than 0.01) than that of patients with low-labeling tumors. When the p105-labeling rate and the clinicopathologic parameters were entered simultaneously into the Cox regression model, the stage of disease, DNA ploidy, p105-labeling rate, and vascular invasion emerged as independent prognostic parameters. These findings indicate that the measurement of p105 may provide useful information for predicting prognosis in advanced gastric cancers.

Pleomorphic xanthoastrocytoma. Ultrastructural, immunohistochemical, and DNA cytofluorometric study of a case

A case of right frontal pleomorphic xanthoastrocytoma that occurred in a 7-year-old boy is reported clinicopathologically. The patient underwent surgery on September 29, 1988. Histologic diagnosis of pleomorphic xanthoastrocytoma was made because, in addition to the unique pleomorphic histologic features, positive glial fibrillary acidic protein in immunohistochemical staining and characteristic ultrastructural features, i.e., cytoplasmic intermediate fibrils and lipid vacuoles, basal lamina, and abundant reticulin networks were demonstrated. The DNA cytofluorometric analysis of the nuclei of the tumor cells disclosed the main mode to be diploid with polyploid classes (4, 8, 16, and 32C) without any aneuploidy. Despite the presence of many pleomorphic nuclei, DNA histogram of the tumor disclosed very few DNA synthetic cells indicating a biologically inactive nature of the tumor. The patient is still alive and totally asymptomatic 20 months postoperatively.

DNA in human glioblastomas. A flow-fluorescence cytometrical examination of 96 tumors

The Flow-Fluorescence Cytometric Method (FCM) was applied to investigate the DNA content and the ploidy outlines of each of 96 glioblastomas. No specific DNA pattern was detected, possibly because of the tangle morphology of these variable tumors. Due to their capricious growth the DNA distribution proved to fluctuate greatly. Thus, the series, arranged according to increased PI (proliferation index) values, exhibited a wide spread within a total range from 7.1-97.15% (mean 39.3%) PI. A threefold subdivision of main types (I-III) appears to be of practical use for clinical prognostic assessment: "diploid" tumors with a PI range up to 10% (N = 7) are followed by "abnormal" chiefly tetra- and hyper-tetraploid tumors up to PI values about 30% (N = 21). The third category includes cases showing excessive "aneuploidy" combined more and more with polyploidy and valid stemlines, up to the PI maximum of about 97 rel.% (N = 68). Thus, in 89 tumors clear pathological changes of DNA content can be decoded; of these 68 (76.4%) express a considerable aneuploidy and polyploidy respectively.

Flow cytometry using paraffin-embedded tissue: five years on

The use of paraffin-embedded tissue for flow cytometry is reviewed. A number of technical modifications of the original 1983 method have been described, aimed at improving the accuracy of DNA measurements by minimizing cell debris or reducing coefficients of variation, and at simplifying sample preparation. Over 100 clinical studies have now been reported, mainly assessing the effect of DNA index on prognosis, and those published up until mid-1988 are summarized in an appendix. More recently there have been developments in the use of monoclonal antibodies to measure oncogene products or proliferation markers in addition to DNA content. Detailed clinical evaluation and standardization of these more sophisticated methods is still some way ahead, but as was the case with DNA index, the use of archival material from patients whose outcome is already known should speed this process.

Flow cytometric analysis of pituitary tumors. Correlation of nuclear antigen p105 and DNA content with clinical behavior

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content was performed on nuclear suspensions from 12 paraffin-embedded pituitary macroadenomas and one pituitary carcinoma and correlated with clinical outcome. Median follow-up was 41 months (range, 33 to 48 months). Three of the 13 tumors (23%) had an identifiable aneuploid peak. Of the four tumors that recurred or metastasized, only one was aneuploid. Nuclear antigen analysis of all diploid tumors showed enhanced p105 expression in G2M phase cells compared to G0G1 cells. The G2M/G0G1 fluorescence ratio for p105 was consistently higher (P less than 0.05) for the three diploid tumors that recurred (median, 1.32 arbitrary fluorescence units; range, 1.27 to 1.80) than for the seven nonrecurrent diploid tumors (median, 1.20 arbitrary fluorescent units; range 1.14 to 1.22). These findings indicate a low incidence of DNA aneuploidy among pituitary tumors and suggest that for diploid adenomas, measurement of p105 may provide information useful in predicting prognosis and directing postoperative adjuvant therapy.