Consensus review of the clinical utility of DNA content cytometry in prostate cancer

Origins and clinical implications of aneuploidy in early bladder cancer

Cytogenetic and flow cytometric studies in a variety of human solid tumors have suggested that gross aneuploidy may arise by a process of abrupt chromosome complement doubling followed by gradual chromosome loss. However, this sequence has not been demonstrated directly in serial studies in individual patients in vivo. The purpose of this study was to search for evidence of chromosome complement doubling and subsequent chromosome loss in flow cytometric ploidy patterns in serial bladder washings and/or biopsies from individual patients with early bladder cancer. Fifty-two patients with noninvasive bladder cancer were followed with serial flow cytometric DNA studies for periods ranging from 5.1 to 42.7 months (median 15.1 months). Serial changes in DNA ploidy and S phase fractions were recorded and correlated with histologic and/or cytologic findings, response to treatment and clinical outcome. The data suggest a series of genetic evolutionary changes in early bladder cancer that include the initial development of peridiploid aneuploidy and repeated rounds of DNA content doubling with chromosome loss in patients with progressive disease. It is likely that gross DNA aneuploidy, and more specifically, DNA multiploidy and DNA hypertetraploidy, all arise by this mechanism. The sequence of DNA diploidy, peridiploid aneuploidy, near-tetraploidy, hypotetraploidy and hypertetraploidy is associated with a progressive increase in S phase fraction, and with increasing tumor grade; late steps in this ploidy sequence were often present in tumors that were refractory to local therapeutic measures and tumors that developed deep tumor invasion and/or distant metastases. We conclude that DNA multiploidy and hypertetraploidy are markers of advanced stages of genetic evolution in human bladder cancer.

Aneuploidy in breast cancer: a fluorescence in situ hybridization study

Although ploidy is associated with the development and progression of most breast cancers, the value of flow cytometric ploidy as a clinical prognostic factor remains controversial. The technique of fluorescence in situ hybridization (FISH) can be used not only to determine overall ploidy, but also to assess the over-representation or under-representation of specific chromosomes in interphase cells. This information may be of prognostic value. We studied 84 primary breast cancers and 20 metastatic tumors by FISH, using chromosome-specific fluorescent centromeric probes. Of these, 100 cases were also studied by DNA flow cytometry. The FISH studies were concordant with DNA flow cytometry with regard to distinguishing aneuploid from diploid tumors in 78% of cases. The FISH data suggested that aneuploidy arises by a process of chromosome complement doubling with subsequent chromosome loss. In tumors that exhibited evidence of more than one round of chromosome complement doubling, the selective accumulation of multiple copies of specific chromosomes or chromosome segments was common. Multiple copies of chromosomes centromeres 1, 3, and 17 were accumulated selectively in the cells of individual tumors more frequently than chromosomes centromeres 7, 11, and 16. Multiple copies of chromosomes centromeres 10 and 20 were selectively accumulated only rarely, if at all. Aneuploidy in breast cancer can be divided into distinct stages using fluorescence in situ hybridization techniques. The stages of aneuploidy provide potential landmarks in the genetic evolution of this disease with possible links to chromosome-specific evolutionary changes.

DNA heterogeneity determined by flow cytometry in prostatic adenocarcinoma--necessitating multiple site analysis

Although DNA ploidy analysis of prostate cancer is generally associated with grade, stage, clinical outcome, and responsiveness to androgen therapy, one possible reason cited for contrary reports may be tumor heterogeneity. A preliminary report using flow cytometric analysis of punch biopsies demonstrated DNA heterogeneity in five of nine patients. We evaluated 75 patients by cutting whole mounts of formalin fixed prostatectomy tissue every 0.6 cm. All malignant areas and a selected normal area were circumscribed, excised, remounted, and 1-3 50 mu thick sections removed. The nuclei were extracted by a Hedley technique and the DNA stained with propidium iodide. Each whole mount had an average of 1 distinct malignant area (range of 1-6 areas per whole mount block). Nuclei were analyzed on a Becton Dickinson (San Jose, CA) FACScan flow cytometer equipped with RFIT DNA software program. After excluding histograms with CVs > 8.0% and/or "suspicious" diploid histograms having a right "shoulder," 75 or 87 patients still had > or = 2 malignant sites available for analysis (average 4, range 2-9 malignant sites/patient). The 322 histograms had an average CV of 4.4%. Thirty of 75 patients (40%) showed DNA heterogeneity in multiple samples taken from the same prostate. There were 37 prostates with only diploid (D), 1 with only tetraploid (T), 7 with only aneuploid (A), 20 with D plus A, 7 with D plus T, 2 with D plus T plus A, and 1 with a D plus suspected hypodiploid DNA content. Exclusion of the tetraploid and "near diploid aneuploid" cases still resulted in 16% (12/75) of the patients having a diploid versus aneuploid DNA content heterogeneity. Because 40% of the prostates contained a different ploidy depending on which area was sampled, this report suggests multiple sites of malignancy must be analyzed to more accurately assess the ploidy status of prostatic adenocarcinoma.

Influence of dihydrotestosterone, epidermal growth factor, and basic fibroblast growth factor on the cell kinetics of the PC3, DU145, and LNCaP prostatic cancer cell lines: relationship with DNA ploidy level

The cell kinetics (percentage of cells in the S+G2 phases of the cell cycle) and the DNA ploidy levels (nuclear DNA content) were determined in 108 samples each of the PC3, DU145, and LNCaP prostate cancer models. This was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. Two to three hundred cell nuclei were analyzed for each of the 324 samples under study. The three cell lines were submitted to experimental conditions including the addition of dihydrotestosterone (DHT), epidermal growth factor (EGF), and basic fibroblast growth factor (bFGF), either alone or in combination, to the culture media. The results show that under the present culture conditions, the PC3 cell line was DHT-, EGF- and bFGF-insensitive. In contrast to what is generally reported in the literature, the DU145 cell line was DHT- and EGF-sensitive under the present culture conditions, but bFGF-insensitive. The LNCaP cell line was DHT-sensitive, but EGF- and bFGF-insensitive. While mainly tetraploid, the three cell lines nevertheless exhibited a significant level of heterogeneity in their nuclear DNA content distributions. Indeed, the proportions of non-tetraploid (diploid, hyperdiploid, triploid, hypertriploid, hypertetraploid, polymorphic) DNA histograms were 14% in the PC3, 16% in the DU145, and 29% in the LNCaP cell lines. These results suggest that the DNA ploidy level would not influence the hormone sensitivity level in the cell lines since they had significantly distinct hormone sensitivity profiles while remaining mainly tetraploid.

Three parameter flow cytometric analysis for simultaneous detection of cytokeratin, proliferation associated antigens and DNA content

The analysis of the cell cycle distributions by univariate flow cytometric DNA measurement has been widely applied in the clinic to determine kinetic parameters of human malignancies. A common problem with measurements of cell cycle phase distributions in tumor biopsy material is the presence of non-malignant diploid cells. Furthermore, such a static measurement might not be accurate enough to describe the dynamic process of cell proliferation. For this purpose alternative methods have been developed to include BrdUrd incorporation or the presence of intrinsic proliferation associated markers such as PCNA or Ki67-Ag into the analysis. However, the presence of nonmalignant diploid cells will influence also these bivariate analyses, especially in case of DNA-diploidy of the tumor cells. Here we present a three parameter flow cytometric assay based on the simultaneous detection of cytokeratin, DNA and a proliferation associated marker, such as BrdUrd, PCNA or Ki67-Ag. Based on the presence of cytokeratin, epithelial cells can be selected for a detailed cell cycle analysis. This method can be applied to frozen tissue, which makes this assay useful for multicentre clinical studies.

DNA ploidy and proliferation heterogeneity in human prostate cancers

DNA ploidy determinations have been shown to have clinical application in predicting disease progression, survival, or response to anti-androgen therapies in prostate carcinomas. Since intra-tumor heterogeneity may have a profound effect on DNA measurements, we determined the frequency of DNA ploidy and proliferation (here S-phase fraction) heterogeneity in early prostatic carcinomas, and estimated the potential impact of heterogeneity on predicting disease course, survival, or response to therapy. Using image and flow cytometric analysis of archival, paraffin-embedded prostate tumors, we measured DNA ploidy in individual foci of prostatic carcinoma in stage T1a, T1b and T1c disease. Image analysis studies included the use of Feulgen stained tissue sections, and a comparison of these results with flow cytometric DNA ploidy determinations on nuclei isolated from the same tumor foci. Flow cytometry was also used to measure DNA Index and tumor S-phase fraction, in some cases using multiparameter analysis of isolated nuclei to determine DNA content and the level of the proliferation-associated antigen, p105. Our results indicate that DNA aneuploid foci of prostate carcinoma are infrequently seen in stage T1a disease (13% of the individuals studied), and that the presence of both DNA diploid and aneuploid foci in the same sample is seen in less than 10% of these individuals. Stage T1b and T1c tumors containing only DNA diploid nuclei are seen, though these are likely most common in low volume, low Gleason grade tumors. By using flow cytometry to compare these results with those using image analysis of the same tumor foci, we demonstrated that the majority (> 75%) of these aneuploid tumors are DNA tetraploid. Our data on prostate tumor S-phase fractions indicate that DNA diploid tumors generally have a lower S-phase than DNA aneuploid foci (including comparisons of DNA diploid and aneuploid foci in the same prostate tumor). These results support the model that early prostate tumors are DNA diploid and have a low S-phase, and that these tumors likely evolve to DNA tetraploid tumors with a similar low S-phase fraction.

Cytogenetic heterogeneity and histologic tumor growth patterns in prostatic cancer

Twenty-five prostatic adenocarcinomas were studied for the presence of intratumoral cytogenetic heterogeneity by interphase in situ hybridization (ISH) to routinely processed tissue sections. ISH with a chromosome Y-specific repetitive DNA probe provided a model to investigate patterns of chromosomal heterogeneity within and between different pathological grades. The Gleason grading system was used, since it is based on a detailed classification of growth patterns. Heterogeneity with respect to ploidy of the tumor was examined by ISH with a repetitive DNA probe specific for chromosome 1. The ploidy status of these cancers was confirmed by DNA flow cytometry (P < 0.001). Cytogenetic heterogeneity at the (Y) chromosomal level was observed between Gleason areas, within one area, and even within single tumor glands. The different patterns of chromosomal heterogeneity were seen in all tumor grades and stages. Differences in ploidy status were also found following the aforementioned histological patterns, again, in all grades and stages. Intraglandular heterogeneity was most frequently seen. No correlation was found between cytogenetic heterogeneity and proliferative activity (Ki-67 immunostaining). In contrast to current views on clonality, suggesting regional separation of subclones with different DNA content, this study demonstrates that these subclones can be interspersed.

Cellular proliferation in prostatic adenocarcinoma as assessed by bromodeoxyuridine uptake and Ki-67 and PCNA expression

Prostatic carcinomas vary in their biological potential, even when stratified by grade and stage. Measurement of cellular proliferation by various methods has been shown to correlate with outcome for several human cancers, including prostatic carcinoma. Uptake of bromodeoxyuridine (BrdUrd), a thymidine analogue, has been accepted as a measure of cellular proliferative rate. However, the technique is somewhat complex, requiring incubation with fresh tissue. We compared cellular proliferation as measured by BrdUrd uptake with two more simple immunohistochemical methods in 44 prostatic adenocarcinoma specimens and correlated the results with standard clinical parameters. The tissue was obtained via needle biopsy, channel transurethral resection, and radical prostatectomy. Specimens were incubated in vitro with BrdUrd and then fixed and paraffin embedded. Sections were immunohistochemically stained with antibodies to BrdUrd, proliferating cell nuclear antigen (PCNA), and Ki-67. At least 1,000 cells were scored, and a labeling index (LI) was calculated (number of positive cells/total number of cells). The mean LI determined by all three indices was low (BrdUrd = 3.0, PCNA = 7.0, Ki-67 = 3.4), consistent with the knowledge that prostatic tumors grow slowly. In 36 patients who had not been treated at the time of analysis, the LI as determined by all three methods correlated well with clinical stage and pathological grade. Furthermore, the LIs discriminated between those with tumor confined to the prostate and those with extension to the seminal vesicles, lymph nodes, or bone (P = 0.003, 0.004, 0.008 for BrdUrd, PCNA, and Ki-67, respectively). The LIs for PCNA and Ki-67 correlated well with that for BrdUrd (r = 0.84; r = 0.85), while the LIs for Ki-67 and PCNA correlated slightly less well with each other (r = 0.78). PCNA and Ki-67 expression appear to reflect essentially the same biological process as BrdUrd uptake. Either can substitute for BrdUrd as a measure of cellular proliferation, and Ki-67 seems to offer the fewest technical problems.

Flow cytometry in the diagnosis of cancer

Flow cytometry has rapidly expanded from basic research to clinical laboratories mainly due to its unique characteristics regarding cell analysis. Among the clinical uses of flow cytometry cancer represents one of the most relevant. Several applications of flow cytometry can currently be applied to the study of cancer, including the detection of tumour cell DNA aneuploidy, the analysis of tumour cell proliferation and the immunophenotyping of leukemias. Although standardized flow cytometry protocols for these applications are scanty, the clinical value has been clearly established. The presence of DNA aneuploidy and a high proportion of S-phase tumour cells have been associated with tumour malignancy and a poor prognosis. The immunophenotype of leukaemia is of great help both for the diagnosis and classification of chronic lymphoproliferative disorders and acute leukaemias, especially in acute lymphoblastic leukemia cases and the M0, M3-variant, M6 and M7 acute myeloblastic leukaemia subtypes. In addition, it allows the identification of relatively rare leukemia cases such as the biphenotypic and the Nk-cell lineage leukemias. The development of flow cytometry is continuously bringing new applications into the clinical laboratory in the area of cancer diagnosis.

The prognostic information of DNA ploidy and S-phase fraction may vary with histologic grade in endometrial carcinoma

DNA ploidy and S-phase fraction (SPF) were determined by flow cytometry on paraffin-embedded tumor material from 243 patients treated during 1980-1985. Patients with well differentiated and moderately differentiated tumors without solid areas (n = 351) formed a low-risk group (corrected 5-year survival 90%). Twenty-four patients, dead of disease within 5 years, were compared with 52 survivors. The estimated death risk was higher for those with SPF > or = 8.0% compared with those with SPF < 8.0% (odds ratio = 18.2; p < 0.001). SPF was the only independent prognostic factor in a multivariate analysis also including age, clinical stage and grade of differentiation. Patients with moderately differentiated tumors with solid areas or poorly differentiated tumors (n = 208) were regarded as a high-risk group. There was a difference in survival according to ploidy; the corrected 5-year survival was 75% for 106 patients with diploid tumors compared with 44% for those with non-diploid tumors (p < 0.0001). In a multivariate analysis DNA ploidy, age and clinical stage were independent prognostic factors, whereas SPF was no longer significant. Thus, DNA ploidy and SPF have different prognostic values depending on histological grade of endometrial carcinoma.

Prediction of pathologic stage and postprostatectomy disease recurrence by DNA ploidy analysis of initial needle biopsy specimens of prostate cancer

BACKGROUND

DNA ploidy determination of carcinomas in radical prostatectomy specimens has shown significant correlation with patient outcome, but the predictive value of ploidy status of cancers obtained by transrectal ultrasound-guided needle biopsies has not been studied extensively.

METHODS

Eighty-nine paired needle biopsy specimens (NBX) and radical prostatectomy (RPX) specimens from patients with early clinical stage (A2-B2) prostate cancer were evaluated for DNA content by image analysis of Feulgen stained tissue sections. Findings were compared with Gleason grading on the same specimens by univariate and multivariate analyses for prediction of local tumor invasion, metastasis, disease recurrence, and serum prostate specific antigen concentration during a 0.9-6.0 year clinical follow-up period.

RESULTS

There was excellent correlation of ploidy status between NBX and RPX specimens (P < 0.0001); NBX and RPX grades did not correlate. On RPX specimens, aneuploid status correlated with high tumor grade (P < 0.0005). Aneuploidy in NBX specimens was associated with a twofold higher rate of extracapsular spread (ECS) (P = 0.04). Aneuploid NBX tumors featured a tenfold greater frequency of metastasis than did diploid NBX tumors (P < 0.005). Radical prostatectomy grade correlated with ECS (P < 0.001) and presence of metastatic disease (P = 0.04). On multivariate logistic regression analysis, aneuploidy in both NBX and RPX specimens was the most significant variable and independently predicted the presence of metastasis (P = 0.006 for NBX; P = 0.028 for RPX). Tumor grade of NBX and RPX specimens did not independently predict metastatic disease or disease recurrence, but RPX grade was associated independently with ECS (P = 0.005). Aneuploid NBX tumors recurred after RPX three times more often than did diploid cases, which was significant on univariate (P < 0.001) and multivariate (P = 0.018) analyses using the Cox proportional hazards model. There was no correlation with NBX or RPX Gleason score and disease recurrence. Preoperative serum PSA concentration did not correlate with tumor grade or ploidy status, but on multivariate analysis, when paired with ploidy status, independently contributed to the propensity for ECS, metastasis, and disease recurrence.

CONCLUSIONS

DNA content analysis of early clinical stage prostate carcinoma needle biopsy specimens by image analysis directly correlates with radical prostatectomy specimen ploidy status and is associated independently, with the presence of metastasis, postprostatectomy disease recurrence, and ECS. Needle biopsy tumor grading did not correlate with prostatectomy grade and did not predict disease outcome accurately.

Significance of aneuploidy

Aneuploidy is a state of abnormal and highly variable DNA and chromosome content found in both hereditary disorders and human malignancy. For two decades flow cytometry has allowed a wide-ranging survey of aneuploidy in clinicopathological series. Although up to 75 per cent of all tumours analysed display aneuploidy, its value as a clinical marker of biological aggressiveness is still uncertain. New technologies promise to reveal more precisely the genetic and subchromosomal changes that constitute aneuploidy and contribute to the malignant phenotype in human tumours.

Progression and survival in prostatic adenocarcinoma: a comparison of clinical stage, Gleason grade, S-phase fraction and DNA ploidy

Clinical data were reviewed in 325 patients with prostatic adenocarcinoma followed up for a mean of 13 years. Paraffin-embedded tumour biopsy specimens from the primary tumours were available for flow cytometry (FCM) in 273 cases. Intra-tumour heterogeneity in DNA index (DI) was found in 4% of the tumours (54 cases were analysed). S-phase fraction (SPF) and DNA ploidy were significantly interrelated. Aneuploidy and high SPF were significantly related to both a high T category and high Gleason score. The progression in T1-2M0 tumours was related to Gleason score (P = 0.009), DNA ploidy (P = 0.006) and SPF (P = 0.007), while the Gleason score (P = 0.0013), DNA ploidy (P = 0.002) and SPF (P < 0.001) had prognostic value in univariate survival analysis. In the entire cohort, the T category (P < 0.001), M category (P < 0.001), Gleason score (P < 0.001), DNA ploidy (P < 0.001) and SPF (P < 0.001) were significant prognostic factors. In Cox's analysis, the M category (P < 0.001), Gleason score (P < 0.001), T category (P = 0.003), age (P = 0.001) and SPF (P = 0.087) were independently related to prognosis. In the T1-2M0 tumours, Gleason score (P < 0.001), T category (P = 0.022) and SPF (P = 0.058) were independent predictors. A novel classification system in which the DNA ploidy or SPF and the Gleason score were combined was found to be of significant prognostic value in all M0 tumours (P < 0.001). The results suggest that FCM can be used as an adjunct to conventional histological assessments for determination of the correct prognostic category in prostatic adenocarcinoma.

DNA analysis by flow cytometry of paraffin embedded core biopsies of the prostate

The majority of literature concerning DNA analysis of prostate cancer involves testing formalin-fixed prostatectomy tissue, fresh or formalin-fixed transurethral resections of the prostate (TURP), or fresh core biopsies. We were interested if flow cytometry could analyze the DNA of formalin-fixed, paraffin-embedded, core biopsies separated into normal versus malignant segments. Of the 50 potentially available samples for analysis representing 11 controls of normal core tissue and 39 core biopsies from the 11 patients, one patient had no normal tissue, one core had no malignancy, and three cores had no tissue visibly remaining in the paraffin blocks for analysis. Therefore, of 45 actual samples available for processing, sometimes representing segments as small as 0.2 cm, separate segments containing malignant glands or normal glands were excised from the blocks, and processed separately by the Hedley technique. Forty-four of the 45 available samples produced interpretable DNA histograms as defined by discernible G0/G1 peaks, a calculable cell cycle analysis, and the qualitative appearance of a "smooth" histogram appearance, reflecting sufficient nuclei were analyzed. This is the first report to our knowledge where flow cytometry has successfully been used to analyze paraffin blocks of core biopsies which were, in addition, separated into malignant versus normal enriched segments.