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Immunohistochemical demonstration of keratin 7 in routinely fixed paraffin-embedded human tissues.

The immunoreactivity of OV-TL 12/30, a monoclonal anti-keratin 7 antibody (Mab), was investigated on frozen as well as paraffin-embedded human tissues. Its reactivity patterns were compared with another well-characterized monoclonal antibody to keratin 7 (RCK 105), and with broadly cross-reacting monoclonal (OV-TL 12/5) as well as polyclonal (pKer) keratin antisera. In frozen sections of normal and malignant human tissues both keratin 7 Mabs gave similar staining patterns. The immunoreactivity for OV-TL 12/30 and the polyclonal antibody (pKer) in tissue sections fixed in 4 per cent formalin or Bouin solution, was completely restored when pretreated with 0.1 per cent pronase, 0.1 per cent trypsin in phosphate-buffered saline (PBS) or with 0.5 per cent pepsin in 0.01 N HCl. Except for loss of immunoreactivity on human normal stomach surface epithelium and glandular mucous cells, Mab OV-TL 12/30 reacted strongly positive with essentially all those formalin- or Bouin-fixed paraffin-embedded tissues that had been shown to stain in non-fixed, frozen sections. In addition to the good correlation in human tissues, a complete correlation between the reactivity on frozen and paraffin-embedded human carcinomas (n = 86) was found as well. While both RCK 105 (anti-keratin 7) and OV-TL 12/5 (anti-keratin 5, 7, 14, 19) did not stain on paraffin-embedded sections, the polyclonal control antiserum (pKer) lost immunoreactivity in some cell types (e.g. mucous cells in compound glands, hepatocytes, pancreatic acinar cells, and proximal and distal convoluted tubules of the kidney). Our study shows that the keratin 7 Mab OV-TL 12/30 is an excellent marker for tumour histopathology since it is reactive in paraffin-embedded formalin-fixed human tissues.

Antibodies, Monoclonal↗

Detection of glyceraldehyde 3-phosphate dehydrogenase messenger RNA using a peptide nucleic acid probe in paraffin-embedded archival specimens.

Although the human genome project has been completed, the functions of many genes remain undetermined. In situ hybridization (ISH) is a key method for identifying cells in which a given messenger RNA is transcribed. Paraffin-embedded specimens remain precious materials for research, but preservation of high-quality RNA in these specimens is not expected unless ample caution was taken during fixation. Peptide nucleic acid (PNA) is a recently developed hybrid molecule with genetic information that has high stability and high affinity to the complementary DNA or RNA. We applied a PNA probe to mRNA ISH of liver specimens obtained by autopsy and embedded in paraffin 28-48 years ago. An 18-mer PNA probe for glyceraldehyde 3-phosphate dehydrogenase was used. Staining was then analyzed in association with morphology by hematoxylin and eosin staining, and with the time between death of the patient and tissue fixation. Notably, specimens fixed with formalin and embedded in paraffin 48 years ago yielded excellent results if the time before fixation was short enough (<8 h). There was a significant inverse correlation between the intensity of ISH staining and the time before fixation. Oligonucleotide PNA probe, albeit at high cost, would increase the value of paraffin-embedded specimens in storage for use in human medical research.

Adult↗

DNA measurement by image analysis of paraffin-embedded breast carcinoma tissue. A comparative investigation.

Measurement of cellular DNA content may provide useful prognostic information in several human neoplasms. The DNA content by image analysis of fresh tissue has been compared with flow cytometry with good correlation, but the use of paraffin-embedded tissue for image analysis has not been studied widely. This study reports the DNA content of 54 breast carcinomas and compares the results of image analysis of paraffin-embedded tissue and results of image analysis and flow cytometry of corresponding fresh tumors. Image analysis of paraffin blocks and fresh tumors showed comparable results in 51 tumors (94%), whereas 47 tumors (87%) were similar by all three methods. The DNA indices from image analysis of fresh and paraffin-embedded tumors showed significant correlation by linear regression analysis (r = 0.96; P less than 0.001). Discordances between image analysis of fresh and paraffin-embedded tumors are the result of technical problems, such as staining and tissue preservation. Discordances between image analysis and flow cytometry reflect the advantages and pitfalls of the two techniques. These data suggest that image analysis of paraffin-embedded tissue is a viable technique that will permit the performance of retrospective studies with long-term follow-up data for the evaluation of the prognostic significance of DNA content.

Breast Neoplasms↗

Comparison of static and flow cytofluorometry for estimation of DNA index and S-phase fraction in fresh and paraffin-embedded breast carcinoma tissue.

DNA index, S-phase and G2/M fractions were measured in breast carcinomas before and after paraffin-embedding. Unfixed tumors were analysed with flow cytometry, while cells prepared from fixed and paraffin-embedded tumors were analysed with both static cytometry and flow cytometry. Cells for static cytometry were prepared with pepsin and cells for flow cytometry were prepared with trypsin. In 44 of 51 paraffin-embedded tumors, analysed with flow cytometry, both DNA index and S-phase fraction could be estimated. There was a strong correlation between the three methods of obtaining DNA indices and S-phase fractions, but this was not true for G2/M fractions. Histograms from flow cytometry of archival material were corrected for background. We conclude that cells prepared from formalin-fixed and paraffin-embedded breast cancer tissue can yield reliable estimation of DNA index and S-phase fraction.

Breast Neoplasms↗

Immunohistochemical detection of p53 overexpression in formalin-fixed, paraffin-embedded sections of endometrial carcinoma.

OBJECTIVE: In the past, immunohistochemical detection of p53 has been possible only in the case of fresh-frozen tissues. However using CM1 and an enhanced method based on microwave heating and protease digestion enabled the immunohistochemical detection of p53 overexpression in formalin-fixed, paraffin-embedded sections of endometrial carcinoma, although very few positive stainings were obtained without such an enhanced treatment. To evaluate the enhancement method, a comparative study was performed on frozen materials and paraffin-embedded samples. METHODS: Fifty-three frozen materials, including normal endometrial glands, endometrial hyperplasias and carcinomas, and paraffin-embedded samples from the same patients were used in this study. PAb1801 (mouse monoclonal antibody) was used to analyse p53 overexpression in the frozen sections, while CM1 (rabbit polyclonal anti-p53 antibody) was used for the paraffin sections. RESULTS: PAb1801 and CM1 staining on normal endometriums and endometrial lesions showed a significant degree of concordance between frozen and paraffin-embedded materials. CONCLUSION: Enhanced immunodetection of p53 in paraffin-embedded tissues will provide a useful alternative to the usual fresh-tissue assay.

Carcinoma↗

Methods in pathology. Identification of T-cell lymphomas in paraffin-embedded tissues using polyclonal anti-CD3 antibody: comparison with frozen section immunophenotyping and genotypic analysis.

While L26 (CD20) is now well established as a B-cell marker of high specificity for use in paraffin-embedded tissues, paraffin-reactive T-cell antibodies (UCHL1, MT1, Leu-22, DF-T1, and MT2) have not shown comparable lineage specificity. A new commercially available polyclonal antibody directed against a synthetic peptide sequence of the CD3 (T-cell) antigen has recently become available for use on paraffin sections. In order to evaluate the utility of this antibody, we studied CD3 expression in conjunction with L26 and leukocyte common antigen (LCA) in 15 T-cell and 20 B-cell non-Hodgkin's lymphomas (NHL), all genotypically confirmed by DNA hybridization and immunophenotyped by immunoperoxidase studies in frozen tissue. Ten of 15 T-cell NHLs (67%) showed unequivocal immunolabeling of neoplastic cells with anti-CD3 in paraffin-embedded tissue. Of the five negative cases, three were lymphoblastic lymphomas, and two were peripheral (postthymic) lymphomas (one anaplastic large cell, Ki-1 positive and one large cell, immunoblastic). CD3 expression was identical in paraffin and cryostat sections (100% concordance). Twenty of 20 B-cell NHLs were positive with L26 and LCA but were negative with anti-CD3. Other neoplasms examined, including three granulocytic sarcomas and 45 nonhematopoietic tumors, were similarly negative with anti-CD3. We conclude that polyclonal anti-CD3 is a sensitive and highly specific T-cell marker in paraffin-embedded tissue and, when used in conjunction with LCA and L26, that it can determine cell lineage in the majority of non-Hodgkin's lymphomas.

Antigens, CD↗

Detection of hepatitis C viral RNA sequences in fresh and paraffin-embedded liver biopsy specimens of non-A, non-B hepatitis patients.

In this study methods of HCV-RNA detection in fresh frozen and formalin-fixed, paraffin-embedded liver biopsies are described. Of 22 untreated chronic non-A, non-B hepatitis patients and 6 control patients, a plasma sample and part of a liver biopsy were freshly frozen for hepatitis C virus (HCV) cDNA-PCR. From 16 of the same non-A, non-B hepatitis patients and from 5 of the same control patients formalin-fixed, paraffin-embedded liver tissue from the same biopsy was available also for HCV cDNA-PCR. In 13 of 22 non-A, non-B hepatitis patients HCV-RNA could be detected in plasma as well as in liver tissue. In the other 9 non-A, non-B hepatitis patients and in 6 control patients, no HCV-RNA was detectable in either plasma or liver tissue. The comparison between HCV cDNA-PCR results in fresh frozen versus formalin-fixed, paraffin-embedded liver biopsies showed that although detection of HCV-RNA in both correlated 100% the quantity of HCV-RNA was lower in the formalin-fixed, paraffin-embedded liver biopsies of 5 of 8 patients for whom end-point dilution titration of liver RNA was performed. We conclude that using the procedures described HCV-RNA can be reliably detected in both fresh-frozen and formalin-fixed, paraffin-embedded liver biopsies and that HCV cDNA-PCR in liver tissue may become an important assay, especially for monitoring anti-viral therapy.

Biopsy↗

Flow cytometric DNA analysis of ulcerative colitis using paraffin-embedded biopsy specimens: comparison with morphology and DNA analysis of fresh samples.

OBJECTIVES: The detection of aneuploidy in colonic mucosa by flow cytometric DNA analysis has been advocated as an indicator of high risk for ulcerative colitis (UC) patients developing colon carcinoma. To date, studies have primarily utilized fresh tissue and have had two limitations: a significant number of possible false-positive findings (aneuploidy in the absence of detectable dysplasia) that may be due to DNA degradation, and the inherent inability to perform retrospective studies. The latter has compromised the adequate assessment of flow cytometric DNA analysis for its clinical utility in UC patients. Our objective was to attempt to overcome the limitations that have been present in DNA analysis by flow cytometry. METHODS: After having established, in our laboratory, an optimal method that allowed reliable DNA analysis on paraffin-embedded mucosal biopsy specimens, we conducted three separate studies to address the above problems associated with DNA analysis with fresh colonic samples: 1) comparison of DNA analysis between fresh and paraffin-embedded colonic mucosal samples from UC patients without dysplasia, 2) correlation between morphology and DNA ploidy on paraffin-embedded tissues showing no dysplasia and various degrees of dysplasia, and 3) sequential analysis of fresh, normal colonic mucosal samples to further evaluate possible causes of false aneuploidy. RESULTS: We observed 1) that there is discordance in DNA ploidy between paraffin-embedded and fresh samples showing no dysplasia in that aneuploidy was found in 33/46 (72%) of fresh samples, whereas 3/40 (7.5%) were aneuploid by biopsies from the corresponding anatomic sites. 2) There is excellent correlation between dysplasia and DNA ploidy results with paraffin-embedded tissue, i.e., none of 16 samples negative for dysplasia, none of seven samples indefinite for dysplasia, and seven of eight samples positive for dysplasia were aneuploid. 3) DNA degradation produced a spurious, near-diploid aneuploid peak in a normal colonic mucosal sample when it was left in saline more than 1 hr before analysis. CONCLUSIONS: The above-described results demonstrate that performing flow cytometric DNA analysis with formalin-fixed paraffin-embedded biopsy samples is feasible and that this technique may provide more reliable ploidy results than does the use of fresh samples, when rapid refrigeration and/or freezing of the fresh samples cannot be accomplished consistently, and will permit retrospective DNA ploidy studies assessing risk of cancer in UC patients.

Adult↗

A new method to extract nuclei from paraffin-embedded tissue to study lymphomas using interphase fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) is difficult to accomplish using thin-sections of paraffin-embedded lymphoid tissue because of the high cellularity and truncated cells that interfere with accurate scoring of individual nuclei. We modified and tested a new technique to isolate individual nuclei from tissue cores of paraffin-embedded tissue processed with xylene, proteinase K, citric acid, and pepsin. The efficacy of this method to study paraffin-embedded tissue was investigated in six normal lymph nodes or tonsils and 32 malignant lymphomas including five mantle cell, five follicular, five Burkitt, five extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue, five anaplastic large-cell, and seven diffuse large B-cell. Fusion of CCND1 and IgH, BCL2 and IgH, c-myc and IgH, and MALT1 and API2 were detected using probes with a dual-fusion FISH strategy. Anomalies involving ALK and BCL6 were detected using break-apart FISH probes. FISH studies were successful for each of the 38 specimens. Chromosome anomalies were detected in each malignant specimen, but not in the normal lymphoid tissue. The correct chromosome anomaly was detected in 22 of 22 specimens with genetic abnormalities that were established by other genetic techniques. This FISH technique is useful to detect chromosome anomalies with high sensitivity and specificity in paraffin-embedded tissue and may provide important diagnostic and prognostic genetic information.

Burkitt Lymphoma↗

Immunohistochemical identification of HCV target antigen in paraffin-embedded liver tissue: reproducibility and staining patterns.

BACKGROUND: Immunohistochemical staining has been applied successfully to detect hepatitis C virus (HCV) antigen in fresh frozen tissue. In paraffin-embedded tissues, however, minimal trials with conflicting results have been reported. AIMS: The present study is a trial to evaluate the identification of HCV antigen in paraffin-embedded liver biopsies using the anti-HCV monoclonal antibody (MAb) TORDJI-22. METHODS: We applied immunohistochemical staining for HCV in 56 paraffin-embedded liver biopsy specimens, 46 from patients seropositive for HCV-RNA and 10 control liver biopsy specimens. The TORDJI-22 MAb was applied in dilution 1:40, with overnight incubation. RESULTS: Reproducible staining patterns of HCV antigen in tissues were identified among the majority (42/46-91%) of HCV RNA seropositive cases. The staining pattern was cytoplasmic of hepatocytes, with occasional nuclear hue. It is mainly coarse granular with microvesicular pattern. Three staining patterns were identified: A, diffuse or membranous; B, patchy; and C, occasional paranuclear. None of the control samples showed a similar staining pattern. CONCLUSION: Immunohistochemical identification of HCV antigen is easy to apply in paraffin-embedded liver biopsy specimens when the optimal detection techniques are applied. The staining pattern is reproducible, being mainly coarse granular cytoplasmic. Cross reactivity with hepatitis B virus antigens was not detected.

Biopsy, Needle↗

Flow cytometric analysis of head and neck carcinoma DNA index and S-fraction from paraffin-embedded sections: comparison with malignancy grading.

Archival, paraffin-embedded, pathology specimens representing pretreatment tissue biopsies from 73 patients with epidermoid carcinoma of the head and neck were analyzed for DNA Index and %S-phase cells by flow cytometry and were scored for quantitative histomorphology. The DNA fluorescence/light scatter size patterns derived from paraffin-embedded specimens were shown to be essentially the same as those from mechanically disaggregated, ethanol-fixed cells obtained from the same tissue specimen. Patterns ranged from lymphocyte-like to highly abnormal DNA Index cytokinetic patterns. The DNA Index values ranged from 0.70 to 3.50 (median 1.42), with an aneuploidy frequency of 63/73 (86%). DNA distribution %S ranged from 4% to 45% (mean 19), with the microscopic malignancy grading showing broad heterogeneity (mean 2.1, range 1.0-3.0, where 1.0-1.7 = well differentiated, 1.8-2.3 = moderately differentiated, 2.4-3.0 = poorly differentiated). Cross-comparison of these data showed that (1) the tumor %S was dependent on DNA Index (higher %S at higher ploidy), (2) low to high malignancy tumors were randomly distributed between diploid/near diploid tumors and high-degree DNA abnormality tumors, and (3) proliferative activity values broadly overlapped between low to high malignancy scored tumors. However, those carcinomas characterized by high DNA Index (greater than or equal to 1.50) and high %S-phase fractions (greater than or equal to 20) had a five fold higher incidence of high-degree malignancy, invasive tumors than diploid/near diploid (%S less than or equal to 19) tumors.

Biopsy↗

Detection of hepatitis B virus DNA in paraffin-embedded liver tissues in chronic hepatitis B or non-A, non-B, hepatitis using the polymerase chain reaction.

We developed a polymerase chain reaction assay for the direct detection of hepatitis B virus in paraffin-embedded liver tissue and applied this assay to determine whether hepatitis B virus DNA exists in livers with chronic hepatitis non-A, non-B. Fifty five liver biopsy samples were studied: 11 from patients with HBeAg-positive chronic hepatitis (paraffin-embedded) and 44 from patients with chronic hepatitis non-A, non-B (21 paraffin-embedded; 25 fresh frozen). Thirty three (75%) of the non-A, non-B cases were positive for hepatitis C virus antibodies. Approximately 1 to 10 ng of DNA was extracted from the paraffin-embedded tissue and amplified using oligonucleotide (23-mer) primers specific for the S gene (positions 261 to 692). The beta-globin gene was used as an internal control for sensitivity because this is a single copy gene and allows for relative quantification. In each of the chronic hepatitis B livers, the expected 432-base-pair amplification product for hepatitis B virus DNA and beta-globin gene product were both detected. On the other hand, in the 21 paraffin-embedded chronic hepatitis non-A, non-B livers, no hepatitis B virus DNA was detected, although beta-globin gene was observed in all. Furthermore, in all 25 frozen non-A, non-B livers, beta-globin gene was observed, but no hepatitis B virus band was seen. The limit of detection of hepatitis B virus DNA by this method was estimated to be one genomic copy of hepatitis B virus DNA per cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Extraction and amplification of DNA from formalin-fixed, paraffin-embedded tissues.

Formalin-fixed, paraffin-embedded tissue (PET) is an invaluable resource for retrospective molecular genetic studies, but the extraction of high-quality genomic DNA from the PET may be problematic. We report a simple method that significantly improves the ability to amplify DNA recovered from formalin-fixed PET. Based on the standard procedure of a commercially available DNA preparation kit, the QIAamp DNA mini kit or the HighPure DNA preparation kit, we developed this method by eliminating the xylene/ethanol extraction step and adding a heat-treatment step. With this method, we have observed a five- to 10-fold increase in amplification efficiency of a fragment in a range of 90 to 386 base pairs. We also have obtained much higher amplification efficiencies for a multiplex polymerase chain reaction.

Base Sequence↗

Direct quantification of gene expression in homogenates of formalin-fixed, paraffin-embedded tissues.

Formalin-fixed, paraffin-embedded (FFPE) tissues represent an important source of archival materials for gene expression profiling. We report here the development of a modified branch DNA assay that allows direct quantification of messenger RNA (mRNA) transcripts in homogenates from FFPE tissue sections without the need for RNA isolation and reverse transcription into cDNA. Formalin fixation essentially has no effect on the branch DNA assay, and RNA degradation only marginally reduces the signal by 2- to 3-fold. Under the same conditions, formalin fixation and RNA degradation greatly reduces real-time reverse transcription PCR (RT-PCR) efficiency, reducing signals by as much as 15- and 1400-fold, respectively. Although both technologies can generate biologically meaningful expression profiles from FFPE human lung tumor specimens, the branch DNA assay is more sensitive than real-time RT-PCR under the conditions tested. Our results therefore suggest that the branch DNA assay is an ideal tool for retrospective analysis of gene expression in archival tissues.

DNA↗

Optimization of recovery of RNA from formalin-fixed, paraffin-embedded tissue.

Formalin-fixed, paraffin-embedded (FFPE) tissue is the most common specimen available for application of diagnostic assays on tissue after microscopic examination. Not only is there a substantial archive of tissue available, but FFPE tissue remains the best method of preparation for microscopic examination in a routine clinical environment. Molecular assays, especially reverse transcription and polymerase chain reaction and expression array-based assays, offer significant potential as diagnostic, prognostic, and predictive tools, but require high quality RNA. Herein, we have optimized a reliable RNA extraction method for FFPE tissue. It is based on deparaffinization at high temperature coupled with a 3-day lysis at 65 degrees C. The average total RNA yield is 4.5 to 5.5 pg per 1 microm of archival FFPE tissue, and 260/280 ratios are between 1.80 and 1.95. The extracted RNA has a modal fragment length between 100 and 200 nt by the Bioanalyzer analysis. Although modal lengths of RNA fragments were shorter, reverse transcription and polymerase chain reaction was able to amplify amplicons in range of 300 bp. Pretreatment with RNA, later followed by formalin fixation, did not result in improving the RNA quality, but did improve RNA yield. Our method improves the utility of FFPE tissue for molecular profiling studies.

Animals↗

Detection of equine and bovine T- and B-lymphocytes in formalin-fixed paraffin-embedded tissues.

Formalin-fixed paraffin-embedded sections of equine and bovine lymph nodes, spleen, thymus, and Peyer's patches were incubated with monoclonal antibodies to B-lymphocyte markers BLA.36, B29, and mb-1 and T-lymphocyte markers CD3 and CD5. The monoclonal antibody BLA.36 reacted with 80-90% of lymphocytes in the germinal centers and mantle zones of follicles in lymph nodes, spleen, and Peyer's patches. In addition, 90% of lymphocytes in the marginal zone of the spleen, and variable numbers of lymphocytes within lymph node medullary cords were immunopositive for BLA.36. Antibodies to B29 and mb-1 produced similar staining patterns as BLA.36 with fewer positive cells in the germinal centers and medullary cords. BLA.36, B29, and mb-1 reacted with 30-50% of lymphocytes in the medulla of the thymus and with 5-10% of lymphocytes in the cortex. CD3 and CD5 reacted with 90% of lymphocytes in the paracortex and parafollicular zones of lymph nodes, spleen, and Peyer's patches; 40-50% of lymphocytes in the medullary cords of lymph nodes, and scattered positive cells within follicles. Anti-CD3 antibody reacted with 95% of lymphocytes in the splenic red pulp, but antibodies directed against CD5 reacted only faintly with approximately 5-10% of lymphocytes in the red pulp. CD3 and CD5 reacted with 50-60% of cells in the medulla of the thymus and with 40-80% of lymphocytes in the thymic cortex. The biochemical characterization of the antibodies by Western blotting against lysates of equine and bovine peripheral blood mononuclear cells confirmed that antibodies to BLA.36, mb-1, B29, CD3, and CD5 detected molecules of the same approximate molecular mass as found on lymphoid cells of human beings and rats.

Animals↗

The immunophenotyping of extramedullary myeloid cell tumors in paraffin-embedded tissue sections.

Extramedullary tissue infiltrates of acute myeloid leukemia are rare and often difficult to recognize in routine paraffin-embedded tissue sections. Since appropriate therapy for these tumors depends on their precise identification, we have studied a series of tissues infiltrated with primitive myeloid cells using monoclonal and polyclonal antibodies capable of labeling cells of the myeloid/monocytic system in paraffin-embedded tissue sections. The current retrospective study involved tissues from 15 patients (eight men and seven women) with a mean age of 51 years (range, 23-77). A diagnosis of extramedullary myeloid cell tumors had been made on the basis of routine histology, chloroacetate esterase cytochemical stain, and--in some cases--electron microscopy. Paraffin-embedded tissue sections were cut and stained employing the alkaline phosphatase antialkaline phosphatase (APAAP) immunocytochemical procedure with monoclonal antibodies against leukocyte-common antigen (PD7/26-2B11), restricted components of the leukocyte-common antigen (UCHL1, 4KB5), granulocytes (Mac-387, Leu-M1), leukocytes (MT1, MT2, LN1, LN2), HLA-DR (LN3), and elastase (NP57), as well as polyclonal antibodies against lactoferrin, lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin. Results indicate that antibodies against Mac-387, elastase, and lysozyme are most useful in the recognition of neoplastic myeloid cells. We conclude that tissues containing granulocytic tumors can be identified in paraffin-embedded tissue sections using a panel of antibodies and the APAAP procedure.

Adult↗

Technical and statistical improvements for flow cytometric DNA analysis of paraffin-embedded tissue.

Flow cytometric DNA analysis of paraffin-embedded solid tumors has permitted review of large series of archival tissue in attempts to relate abnormal DNA content to prognosis. Limitations of the technique include: 1) a laborious, time-consuming procedure; 2) variation in technique between laboratories; and 3) lack of an objective method of computing DNA indices. Critical evaluation of our technique has shortened the time involved in dewaxing and rehydration, selectively utilized patient's own normal tissue as the internal standard, proved reproducibility of stored specimens, standardized DNA index computation, and developed a statistical analysis to confirm aneuploidy. These technical improvements and the development of a statistical analysis provide a way to shorten the procedure time and standardize the data generated from flow cytometric DNA analysis so as to improve the quality of retrospective reviews of paraffin-embedded tumors and accelerate the definition of flow cytometry's role as a prognostic indicator.

Breast Neoplasms↗