Significance of multiparameter flow cytometric analysis of ovarian cancer

Morphologic and morphometric features of low grade serous tumours of the ovary

Peritoneal washings from twelve patients with serous tumours of the ovary were studied. Six patients had borderline serous tumours (BSTs), and six had grade one adenocarcinomas. Papanicolaou stained slides were assessed for nine morphologic parameters; background, single cells, size of papillary fragments, contour of papillary fragments, psamomma bodies, cytoplasmic vacuoles, nuclear pleomorphism, nuclear membrane contour, and nucleoli. The slides were destained and restained by the Feulgen method for assessment, with a computer based image analysis system (CAS100, Cell Analysis Systems, Inc., Elmhurst, IL), of DNA content, nuclear size, and nuclear roundness. The contour of the papillary fragments (P = 0.004) and the presence of nuclear pleomorphism (0.019) were distinguishing characteristics. All six BSTs were diploid while three of the six adenocarcinomas had aneuploidy. Two exhibited polyploid DNA distribution and one exhibited diploid DNA distribution. The pooled data for the nuclear size and roundness showed little difference in the modal values, although the nuclei of the adenocarcinoma cells were slightly larger than those of the borderline cells (54 sq. microns vs. 46 sw. microns). However, the coefficients of variation (CVs) for each of these parameters were larger in the adenocarcinoma group than in the borderline group (59.7 vs. 36.4% for size and 33.5 vs. 17.8% for roundness). Although the sample size is small, the data suggest that aneuploidy is rare in borderline tumours. In addition, the presence of papillary groups with irregular contours and nuclear pleomorphism (reflected in higher CVs for nuclear size and roundness) both occur more commonly in adenocarcinomas than in borderline tumours and may be of predictive value in distinguishing the two groups.

Flow cytometric evaluation of ovarian cancer

BACKGROUND

Despite recent advances in the treatment of ovarian cancer, the long-term prognosis for patients with this malignancy appears to depend more on tumor prognostic factors than on treatment regimens. The traditionally used prognostic factors are often subjective and, currently, have not been sufficient to determine individual patient prognosis.

METHODS

Newer techniques of quantitative cytologic testing, including flow cytometry, facilitate the objective evaluation of tumor cell heterogeneity and the identification of additional prognostic factors.

RESULTS

There is good evidence, mainly from retrospective studies, that DNA ploidy is a valuable prognostic indicator in patients with both early-stage and late-stage ovarian cancer. Most of the recent flow cytometric studies have identified ploidy as an independent prognostic factor, with aneuploidy predicting a significantly shorter survival time, even in patients with borderline malignant tumors. Flow cytometric determination of cell cycle information (e.g., S-phase fraction or proliferative index) may represent additional prognostic information and may be used to predict the early tumor response to treatment.

CONCLUSIONS

Although additional prospective studies are needed to establish the exact value of flow cytometric evaluation for ovarian cancer and other gynecologic malignancies, there is little doubt that the prognostic value of this information will influence clinical management of patients with these malignancies in the near future.

Flow cytometric analysis of nuclear DNA content in ovarian tumors. Association of ploidy with tumor type, histologic grade, and clinical stage

The authors undertook a prospective, flow cytometric study of nuclear DNA ploidy in 140 fresh ovarian tumors. There were 43 benign tumors, 27 borderline tumors, and 70 malignant tumors. Results of DNA ploidy analysis were compared to age at diagnosis, menopausal status, tumor size, histologic type, grade, and International Federation of Gynecology and Obstetrics (FIGO) stage. Although the majority of benign tumors were diploid, 19% were aneuploid. Among the benign tumors, DNA ploidy was significantly associated with tumor type and tumor size. All borderline tumors were diploid. Of the 70 malignant tumors, 64% were aneuploid. In the malignant tumors, DNA aneuploidy had significant univariate associations with histologic type, grade, and FIGO stage. By multivariate analysis, DNA aneuploidy remained significantly associated with stage and grade, both known predictors of survival in ovarian cancer. These results indicate that DNA ploidy varies with the aggressive potential of an ovarian cancer and may, at the time of initial diagnosis, provide additional information about tumor prognosis.

Comparative evaluation of fresh, fixed, and cryopreserved solid tumor cells for reliable flow cytometry of DNA and tumor associated antigen

Five different protocols for the short-term preservation of cells used for multiparameter flow cytometric assay of tumour associated antigens (TAA) and DNA were assessed in cell suspensions prepared by mechanical disaggregation of 15 gynecological tumors. The protocols at 4 degrees C were 1) storage in buffer, 2) storage in 50% methanol, and 3) storage in buffer after formalin fixation. Tissues were also cryopreserved as cell suspensions and tissue blocks. When the TAA expression and DNA histograms of the preserved cells were compared with those in fresh cell suspensions, cryopreservation was found to be the best method: TAA expression was well preserved and there was a good correlation between TAA expression and the quality of the DNA histograms, respectively, in fresh and cryopreserved cells (RS: 0.82-0.91, P less than 0.001 for all TAAs). The cell suspensions preserved at 4 degrees C all showed a significant increase in background fluorescence (P less than 0.05) and a reduction in the TAA specific fluorescence (P less than 0.011). Methanol fixation was better than buffered formalin for the proteins studied, though both gave significantly worse results than cryopreservation. The quality of these cell suspensions and the correlation with TAA measurements in fresh cell suspensions deteriorated progressively with time, particularly if they were stored more than a week.

Multi-parameter flow cytometric quantitation of the expression of the tumor-associated antigen SM3 in normal and neoplastic ovarian tissues. A comparison with HMFG1 and HMFG2

SM3 is a monoclonal antibody that reacts with a peptide epitope in the core protein of polymorphic epithelial mucin. Multi-parameter flow cytometry was used to characterize the expression of SM3 and compare it with two related tumor-associated antigens, HMFG1 and HMFG2, in cell suspensions of 44 malignant ovarian tumors, 15 benign ovarian tumors, and 16 normal ovaries. Tumor-associated antigen expression was significantly higher in malignant ovarian neoplasms than in benign neoplasms (P less than 0.001 for all three antigens). SM3 was expressed more specifically in malignant than benign tumors but had a lower affinity than HMFG1 and HMFG2. Multi-parameter flow cytometric evaluation of a panel of monoclonal antibodies can be used to help in choosing the best antibody for immunohistochemistry, imaging, and eventually treatment of ovarian tumors.

Flow cytometric DNA analysis with use of normal lymph node cells as an internal reference standard in ovarian cancer

Fresh frozen and paraffin-embedded tumor specimens of 21 patients with ovarian cancer were investigated by means of flow cytometry. In 4 patients, the fresh frozen tumor specimens (fresh tumor specimens) of ovarian tumors were measured for the DNA ploidy and index. We used the paraffin-embedded normal lymph node tissue specimens which were acquired from retroperitoneal lymphadenectomy as the internal reference standard (IS). In all 21 patients, the paraffin-embedded tumor specimens mixed with a lymph node specimen as an IS (tumor specimen with IS) were measured. In addition, all 21 paraffin-embedded tumor specimens without a lymph node tissue specimen (tumor specimens without IS) were measured. In 4 cases which were measured with the fresh tumor specimens, all 4 tumor specimens with IS had the same patterns of DNA ploidy as the fresh tumor specimens. Of 21 patients, 6 patients showed different DNA ploidy patterns between the tumor specimens with and without IS. Furthermore, all of these 6 patients showed diploidy in the tumor specimens without IS while showing aneuploidy in the tumor specimens with IS. Fourteen (66.7%) of 21 tumor specimens with IS were aneuploidy despite aneuploidy of only 8 (38.1%) tumor specimens without IS. All 4 patients with stage I had diploidy in the tumor specimens with IS, and 13 (81.3%) of 16 patients with stage III or IV had aneuploidy. All 8 patients with diploidy in the tumor specimens with IS had survived for 1-2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

The prognostic value of image analysis in ovarian cancer

Histologic grading is very important for treatment decisions in ovarian cancer. All grading systems contain a significant subjective component, which could be reduced by including objective measurements into the diagnostic decision. Image analysis was used to determine nuclear area and ploidy distributions in 42 patients with epithelial ovarian cancer, and the results were related to tumor grade and clinical outcome. The mean nuclear area, mean optical density, number of hyperploid cells, and the standard deviation between measurements were significantly higher in Grade 2 and 3 tumors compared with Grade 1 tumors, in rapidly progressive tumors compared with less aggressive malignancies, and in recurrent tumors compared with primary lesions. The number of nuclei with very high DNA content was found to be of prognostic importance. Image analysis thus provides additional prognostic information in epithelial ovarian cancer.

Prognostic significance of tumor ploidy in patients with advanced ovarian carcinoma

Fresh tumor specimens obtained from 53 consecutive patients with FIGO Stage III ovarian carcinoma were analyzed by flow cytometry. All patients were treated by a standard protocol: maximal tumor excision and cisplatin/cyclophosphamide/adriamycin chemotherapy, and followed-up for at least 24 months. Thirty-two percent of tumors were diploid (DNA index = 1.00) and 68% aneuploid (DNA index greater than 1.00), with more aneuploid tumors being associated with larger residual tumor and poor cellular differentiation. Patients with diploid tumors were found to survive significantly better than those with aneuploid tumors, in terms of survival rate (65% versus 31%), median survival time (33 months versus 13 months), and mean disease-free interval (17.8 months versus 8.2 months). The influence of the amount of residual tumor after primary surgery on survival was only significant in patients with diploid tumors. Our results support previous findings that tumor ploidy is an important prognostic indicator in ovarian cancer. We found aneuploidy to be associated with a poorer clinical outcome in Stage III disease, regardless of the amount of residual tumor after primary surgery and the degree of cellular differentiation.

Tissue preparation for simultaneous flow cytometric quantitation of tumour associated antigens and DNA in solid tumours

A multiparameter flow cytometric assay for the simultaneous study of tumour associated antigens (TAA) and DNA in fresh solid tumours was devised. Cell suspensions were prepared by disaggregating unfixed solid tumour samples mechanically over a stainless steel mesh. Indirect immunofluorescence was used to identify the TAA, and DNA was stained with propidium iodide. Cell morphology was well preserved, cell clumping was negligible, and high quality indirect immunofluorescence quality indirect immunofluorescence and DNA staining were obtained. The technique is simple, rapid, and reproducible. Multiparameter assays can be developed to study prognostic indicators such as membrane oncoproteins, receptors, and multidrug resistance in solid tumours. With a suitable panel of antibodies the technique might become an aid in the differential diagnosis and biochemical diagnosis of some solid tumours.

Class I histocompatibility antigen expression: a prognostic factor for aneuploid ovarian cancers

Epithelial ovarian cancers with aneuploid DNA content are associated with a poorer clinical course than diploid tumors. Flow cytometric analysis may further categorize aneuploid tumors based on the relative expression of cell surface histocompatibility (HLA) antigens. Surgical specimens from 20 patients with aneuploid tumors were stained using an indirect immunofluorescence method with primary murine monoclonal antibodies W36/22 (class I HLA surface antigens) and L5.1 (irrelevant antibody), counterstained with propidium iodide (DNA stain), and analyzed with the flow cytometer using a computer program to correct staining intensity for cell size. Patients with high or low class I expression were similar with respect to age, stage, histology, grade, and residual disease following surgical debulking; all patients were treated with cisplatin-based chemotherapy. Women with low class I HLA antigen expression had higher progression rates and death rates than patients with high class I HLA expression. Low class I HLA antigen expression is a poor prognostic factor among patients with aneuploid ovarian cancers.

Flow cytometric versus immunohistochemical analysis of ovarian cancer class I antigen expression: differences may represent a defect in antigen expression

Class I antigen expression by ovarian epithelial neoplasms was determined by flow cytometric analysis and an immunoperoxidase technique for each specimen. The numbers of class I positive tumors determined by the methods were compared. The more subjective immunohistochemical analysis and the more objective flow cytometric technique revealed similar results as long as strict criteria for the interpretation of results was applied. Most of the tumor specimens revealed a homogeneous Gaussian distribution of green fluorescence, class I antigen expression, by flow cytometry. There were two specimens that exhibited a less than characteristic type of membrane staining. The antigen-antibody reaction product was expressed in the extracellular matrix, as well as on the cell membrane of certain cells. This may represent a defect in antigen expression and, if so, might alter the immune response to these tumors.

Flow cytometric evaluation of epithelial ovarian cancer

We investigated the prognostic significance of deoxyribonucleic acid content and proliferative activity of tumor cell populations as measured by flow cytometry of the tumor specimens from 115 women with epithelial ovarian cancer. Deoxyribonucleic acid aneuploidy was found in 87 of 115 (76%) of these cancers with a mean deoxyribonucleic acid index of 1.6 and S-phase fraction of 14.7%. The S-phase fraction of the 28 (24%) diploid tumors was 7.0%. Deoxyribonucleic acid ploidy was significantly correlated with survival. S-phase fraction was significantly correlated with ploidy, residual tumor, histology, grade, ascites, time to recurrence, and survival. Diploidy versus aneuploidy were the best discriminating values for deoxyribonucleic acid index and an S-phase fraction of greater or less than 18% for that parameter. Multivariate analysis revealed stage, S-phase fraction, residual tumor, and grade to be independently associated with time to recurrence, and stage, age, S-phase fraction, and largest metastases were factors associated with survival. Deoxyribonucleic acid ploidy did not significantly improve either model. These results suggest that abnormalities of deoxyribonucleic acid content and the proliferative activity of tumor cell populations are reflective of their biologic activity.

Tumour cell activity markers in epithelial ovarian cancer: are biochemical and cytometric indices complementary?

Flow cytometry has enabled the objective assessment of cellular morphology and activity, which can also be biochemically evaluated by measuring products of cellular metabolism, such as cyclic 3'5' guanosine monophosphate (cGMP). Using paraffin-embedded formalin-fixed material obtained from the primary operation, an analysis of the correlation between nuclear ploidy and the proliferative index (PI) as quantified by flow cytometry with pre-treatment urinary cGMP was performed in 40 epithelial ovarian cancer (EOC) patients. The majority of the study group had advanced disease (28 FIGO III/IV) and residual disease (31). All but three (stage I) patients received single agent high dose cisplatinum as first-line therapy (100 mg m-2 x 5); in patients with evaluable disease there was a response rate of 64%. Thirty-one patients have died; the median survival of the study population being 27 months. There was a significant association between cGMP and PI. Significantly more aneuploid tumours had elevated PI values (P = 0.02). No variable predicted response. An initial univariate log rank analysis identified stage, the amount of residual disease, cGMP and PI as prognostic factors. Because of the interrelation between these and other factors and because PI did not conform to the proportional hazards model, a multivariate stepwise discriminant analysis was performed using survival at 36 months (the minimum follow-up for surviving patients) as the end-point. On the basis of this analysis, stage and residual disease were the most important prognostic factors, but cyclic GMP continued to have prognostic value even when these other factors were entered into the predictive model. However, the additional information gained has little clinical relevance.

Cytophotometry in tumor pathology. A critical review of methods and applications, and some results of DNA analysis

In tumor pathology the quantitation of cellular substances can be of diagnostic value. Microscope cytophotometry and digital image analysis and, on the other hand, flow cytometry are supplementary methods for measuring, each with a typical spectrum of application. The methods are predominantly used for DNA analysis: Static and image cytophotometry are applicable to cytologic and histologic slides preferably for identifying stem lines in tumors of heterogenous morphology and in merely circumscribed lesions (e.g., precancerous lesions). On the other hand, sampling errors due to preselection, and the often low number of cells actually measured, may preclude the possibility of exact cell cycle analysis. This is, in fact, an important additional option of flow cytometry resulting from the high resolution of DNA histograms, which is explained by the large number of cells that can be measured in a short period. Sampling errors in flow cytometry may result from the preparation of single cell suspensions which in certain tumor entities may suppress a varying amount of particularly fragile cells or nuclei. The prognostic significance of DNA ploidy, stem line heterogeneity and S-phase fraction is clearly described in quite a number of tumor entities. Independent of its prognostic value, the cytometric identification of stem lines might be particularly useful in the follow-up of tumor patients, where it may indicate the effectivity of systemic therapy. The development of therapeutic concepts is aptly supported by flow cytometric cell cycle analysis which helps to assess the in vitro effect of combined cytostatics on the proliferative process. Moreover, multiparameter analysis of biopsy samples may provide greater accuracy in characterising individual tumor stem lines and may furthermore help to develop improved protocols for the therapy of solid tumors.

Flow cytometry to evaluate acrosome-reacted sperm

Flow cytometry was used in the scoring of acrosome-reacted human sperm. Propidium iodide was used for detection of the nonviability of the sperm. Fluoresceinated pea lectin was used to detect acrosome-reacted sperm. The results obtained by flow cytometry and those obtained by fluorescence microscopy were compared to determine if flow cytometry can serve as a more accurate, faster, and simpler method. It was possible to detect human sperm by flow cytometry. The percentage of propidium iodide labeled sperm determined by flow cytometry was close to that obtained by fluorescence microscopy. Comparison of the percentage of acrosome-reacted sperm determined by flow cytometry and fluorescence microscopy showed that these methods gave very similar results (r = 0.98, p less than 0.001). Objective scoring of more sperm was possible by flow cytometry than by fluorescence microscopy, and flow cytometry was useful as a simple method for evaluation of acrosome-reacted human sperm.