Flow cytometric DNA analysis of fresh prostatic resections. Correlation with conventional prognostic parameters in patients with prostate cancer

The Combination of DNA Ploidy Status and PTEN/6q15 Deletions Provides Strong and Independent Prognostic Information in Prostate Cancer

PURPOSE

Aberrant DNA content has been discussed as a potential prognostic feature in prostate cancer.

EXPERIMENTAL DESIGN

We analyzed the clinical significance of DNA ploidy in combination with prognostic relevant deletions of PTEN and 6q15 in 3,845 prostate cancers.

RESULT

The DNA status was diploid in 67.8%, tetraploid in 25.6%, and aneuploid in 6.8% of tumors, and deletions of PTEN and 6q15 occurred in 17.8% and 20.3% of tumors. Abnormal DNA content and deletions were linked to high Gleason score, advanced tumor stage, and positive nodal stage (P < 0.0001 each). The risk of PSA recurrence increased from diploid to tetraploid and from tetraploid to aneuploid DNA status (P < 0.0001 each). However, 40% of patients with Gleason score ≥4+4 and 55% of patients with PSA recurrence had diploid cancers. This fraction decreased to 21% (Gleason ≥4+4) and 29% (PSA recurrence) if PTEN and/or 6q deletion data were added to ploidy data to identify cancers with an aberrant DNA status. The significance of combining both deletions and ploidy was further demonstrated in a combined recurrence analysis. Presence of deletions increased the risk of PSA recurrence in diploid (P < 0.0001), tetraploid (P < 0.0001), and aneuploid cancers (P = 0.0049), and the combination of ploidy data and deletions provided clinically relevant information beyond the CAPRA-S nomogram. Multivariate modeling including preoperatively and postoperatively available parameters identified the "combined DNA status" as a strong independent predictor of poor patient outcome.

CONCLUSIONS

The combinatorial DNA content analysis involving general (ploidy) and specific events (deletions) has the potential for clinical utility in prostate cancer. Clin Cancer Res; 22(11); 2802-11. ©2016 AACR.

TMPRSS2-ERG gene fusion is not associated with outcome in patients treated by prostatectomy

A significant number of prostate cancers have been shown to have recurrent chromosomal rearrangements resulting in the fusion of the androgen-regulated TMPRSS2 promoter to a member of the ETS transcription factor family, most commonly ERG. This results in ERG overexpression, which may have a direct causal role in prostate tumorigenesis or progression. However, the clinical significance of the rearrangement is unclear, and in particular, relationship to outcome has been inconsistent in recent reports. We analyzed TMPRSS2-ERG gene rearrangement status by fluorescence in situ hybridization in 521 cases of clinically localized surgically treated prostate cancer with 95 months of median follow-up and also in 40 unmatched metastases. Forty-two percent of primary tumors and 40% of metastases had rearrangements. Eleven percent had copy number increase (CNI) of the TMPRRS2-ERG region. Rearrangement alone was associated with lower grade, but not with stage, biochemical recurrence, metastases, or death. CNI with and without rearrangement was associated with high grade and advanced stage. Further, a subgroup of cancers with CNI and rearrangement by deletion, with two or more copies of the deleted locus, tended to be more clinically aggressive. DNA index assessment revealed that the majority of tumors with CNI of TMPRSS2-ERG had generalized aneuploidy/tetraploidy in contrast to tumors without TMPRSS2-ERG CNI, which were predominantly diploid. We therefore conclude that translocation of TMPRSS2-ERG is not associated with outcome, and the aggressive clinical features associated with CNI of chromosome 21 reflect generalized aneuploidy and are not due to CNI specifically of rearranged TMPRSS2-ERG.

Androgen receptor expression and DNA content of paraffin-embedded archival human prostate tumors

BACKGROUND

Androgen receptors (AR) are expressed in human prostate cells and immunohistochemistry has been used for qualitative analysis of AR expression in prostate tumor cells. Quantitative and multiparametric analysis of receptor expression could be of diagnostic and prognostic value in the management of patients on antiandrogen therapy. Multiparametric flow cytometric methods have been developed for analysis of hormone receptor expression and DNA content in nuclei isolated from formalin-fixed/paraffin-embedded human solid tumors. The present study was undertaken for analysis of AR expression and DNA content in archival human prostate tumors.

METHODS

AR expression and DNA content were measured in nuclei isolated by enzyme digestion from thick sections cut from 51 paraffin-embedded human prostate tumors. AR expression in different subpopulations was studied by gated analysis. The relationship among AR activity, DNA content, and histopathological grade was analyzed.

RESULTS

Distinct aneuploid populations were observed in 23% of tumors examined. AR activity was observed in all the specimens and the percentage of AR- positive nuclei in the 48 samples analyzed was <10% (n = 4), 11-50% (n = 39), and >51% (n = 5). Tumor subpopulations with aneuploid DNA content had higher AR expression (percent AR-positive cells and mean log fluorescence) than the diploid subpopulations. No strong correlation was seen between AR expression and histopathological grade of the tumors.

CONCLUSIONS

Flow cytometric analysis of archival prostate tumor can be used for rapid determination of aneuploid DNA content and AR expression in subpopulations of nuclei isolated from formalin-fixed/paraffin-embedded prostate tumor blocks.

Factors that influence the measurement of prostate cancer DNA ploidy and proliferation in paraffin embedded tissue evaluated by flow cytometry

DNA ploidy and proliferation have been shown in several studies to be prognostic markers for prostate cancer. Flow cytometry (FCM) is often used in the determination of ploidy and proliferation. However, FCM cannot readily distinguish among benign epithelium, stromal and inflammatory cells, high grade prostatic intraepithelial neoplasia (HGPIN), and cancer cells. In this study, we evaluated H&E histologic features of 322 radical prostatectomy formalin-fixed, paraffin-embedded tissue blocks used for determining DNA ploidy, percent S-phase (%S), and %S + %G2M by FCM. The microscopic findings included Gleason score, extent of cancer and HGPIN in the tissue block, and presence of a needle track. The amount of cancer in the block was expressed as a percentage of the total tissue surface area in quartiles: < or =25%, 26-50%, 51-75%, and > or =76%. The extent of HGPIN was recorded in rough 5% intervals. Needle track effect was defined as a combination of fibrohistiocytic reaction, fibrin clot, granuloma formation, and chronic inflammation. The associations between these histologic features and DNA ploidy and proliferation (%S and %S + %G2M) were assessed. In multivariate analyses, Gleason score, the amount of tumor in the tissue block, and the extent of HGPIN were significantly associated with ploidy. Gleason score was the only parameter significantly associated with the proliferation measure of %S. If we included %G2M as part of the proliferative fraction of the histogram, however, both Gleason score and the amount of tumor in the block were significantly associated with this measure of proliferation. The presence of a needle track was not significantly associated with DNA ploidy, %S, or %S + %G2M. In summary, prostate cancer DNA ploidy and proliferation results assessed by FCM in paraffin-embedded tissue blocks were associated with the Gleason score, amount of cancer in the tissue block, and extent of HGPIN. However, the presence of a needle track was not associated with the FCM results.

Predicting prostate carcinoma volume and stage at radical prostatectomy by assessing needle biopsy specimens for percent surface area and cores positive for carcinoma, perineural invasion, Gleason score, DNA ploidy and proliferation, and preoperative serum prostate specific antigen: a report of 454 cases

BACKGROUND

DNA ploidy analysis of prostate carcinoma is a generally accepted prognostic marker, particularly when tumors are extraprostatic at the time of surgery. In the past decade, the DNA content of prostate carcinoma frequently has been assessed in needle biopsy specimens based on the assumption that ploidy, in conjunction with serum prostate specific antigen (PSA) and Gleason score, provides valuable pretreatment information.

METHODS

Between 1995 and 1998, the authors identified a consecutive series of 454 prostate carcinomas, verified by needle biopsies and followed by radical retropubic prostatectomies (RRP). Based on the needle biopsies, DNA ploidy and MIB-I immunostaining were measured by digital image analysis (DIA). The authors also quantified the percent of nuclei in four categories from the DNA histograms. The DIA data were combined with the age of the patient at diagnosis, the serum PSA, Gleason score, percent cores and percent surface area positive for carcinoma, and status of perineural invasion in multivariate models using tumor volume and risk of extraprostatic extension (EPE) at RRP as the outcome variables.

RESULTS

Joint predictors of tumor volume at RRP were the percent cores positive for carcinoma (P < 0.0001), serum PSA (P < 0.0001), the percent surface area positive for carcinoma (P < 0.0001), and the percent nuclei classified by DNA quantification to be in the "S-phase" category (P = 0.03). Joint predictors of risk of EPE were the percent cores positive for carcinoma (P = 0.0004), a Gleason score of 7 (P < 0.0001), a Gleason score of 8 or 9 (P < 0.0001), serum PSA (P = 0.006) and perineural invasion (P = 0.02).

CONCLUSIONS

After adjusting for traditional prognostic markers, DNA ploidy interpretation and MIB-I quantitation of prostate carcinoma did not appear to jointly predict either outcome variable in the multivariate models. However, a quantitative measure related to both ploidy and proliferation, the percent of nuclei in the putative "S-phase" category from the DIA histograms, was found to jointly predict for tumor volume.

Stage B Prostate Cancer: Correlation of DNA Ploidy Analysis With Histological and Clinical Parameters

BACKGROUND: The ability to accurately predict tumor behavior and patient survival is a problem in managing patients with prostate cancer. Prognostic variables in predicting death from tumor include prostate-specific antigen (PSA) level, histological grade, and clinical stage. Observer subjectivity is inherent in determining grade and stage; thus, criteria that are more objective are needed to identify patients for appropriate treatment. METHODS: The authors correlated flow cytometric nuclear DNA ploidy with Gleason score, PSA level, and recurrence risk in patients who underwent radical retropubic prostatectomy and bilateral pelvic lymphadenectomy between 1987 and 1993 for histopathologic stage B prostate cancer (T2, N0, M0). RESULTS: Of the tumors analyzed, 64% were DNA diploid with a low proliferative fraction, 25% were DNA diploid with a high proliferative fraction, and 11% were DNA aneuploid. DNA aneuploidy was associated with high Gleason grade (7-10). All Gleason grade 10 tumors were DNA aneuploid. Both DNA aneuploidy and high proliferative fraction (S+G2M) were statistically correlated with high Gleason grade and adverse prognosis but not with PSA level or patient age. CONCLUSIONS: A direct relationship is shown between both DNA aneuploidy and a high proliferation index with aggressive biological behavior in stage B prostatic cancer. Objective tumor criteria are needed to choose treatment more selectively for individual patients.

Predictability of PSA failure in prostate cancer by computerized cytometric assessment of tumoral cell proliferation

OBJECTIVES

To evaluate the relationship of DNA ploidy and cell proliferation (CP) with Gleason score (GS) and clinical outcome in prostate cancer.

METHODS

Sixteen patients with benign prostatic hyperplasia (BPH) and 65 patients with prostate cancer classified by GS (four groups: 2 to 4, 5 to 6, 7, and 8 to 10) were studied. All patients with carcinoma underwent prostatectomy and were separated into prostate-specific antigen (PSA) failure and nonfailure groups (failure if PSA 0.1 ng/mL or more three times after surgery). Tumoral CP (Ki-67 inmunostaining and SG2M phase) and DNA ploidy were evaluated by computerized cytometry.

RESULTS

BPH were diploid with low CP (8% SG2M cells or less). Carcinomas were either diploid with high CP (greater than 8% SG2M cells) or aneuploid. CP was significantly higher (P <0.001) in tumors with GS 7 or greater than in tumors with GS less than 7 (mean percent Ki-67 cells 18.3% versus 7.8%, respectively). PSA failure increased with GS (7.1% in GS 2 to 4, 21% in GS 5 to 6, 28.6% in GS 7, and 50% in GS 8 to 10), as well as with aneuploidy (18.5% in diploid tumors versus 72.7% in aneuploid tumors). Those experiencing PSA failure had significantly higher (P <0.001) CP than those not failing (mean percent Ki-67 cells 24% and mean percent SG2M 30.4% versus 8.7% and 13.5%, respectively). Cox regression analysis showed GS, DNA ploidy, Ki-67, and SG2M to each be univariately prognostic for time to PSA failure; however, Ki-67 and SG2M were more highly significant (P <0.0001 for both) than GS (P = 0.007) or DNA ploidy (P = 0.002). After adjusting for either SG2M or Ki-67 measures of CP, neither ploidy nor GS contained additional prognostic value.

CONCLUSIONS

Tumor CP and DNA ploidy can be reliably determined in prostate cancer by computerized cytometry. On the basis of our preliminary results, CP correlates well with GS and predicts PSA failure better than DNA ploidy or GS.

Racial differences in clinically localized prostate cancers of black and white men

PURPOSE

Tumor grade, deoxyribonucleic acid (DNA) ploidy, proliferation, p53 and bcl-2 expression were examined in clinically localized prostate cancers of black and white American men to learn whether these features showed racial differences.

MATERIALS AND METHODS

A total of 117 prostate cancers (43 black and 74 white patients) obtained at radical prostatectomy for clinically localized disease were assigned Gleason scores by a single pathologist. Enzymatically dissociated nuclei from archival prostate cancers were examined by DNA flow cytometry using propidium iodide staining and the multicycle program to remove debris and sliced nuclei and to perform cell cycle analysis. For immunostaining after microwave antigen retrieval we used a DO-1/DO-7 monoclonal antibody cocktail for p53 and the clone 124 antibody for bcl-2.

RESULTS

Significantly more black than white men had Gleason score 7 tumors. The DNA ploidy distribution of Gleason 6 or less tumors was similar for both races. As anticipated, the ploidy distribution of higher grade prostate cancer in white men was more abnormal but, unexpectedly, this was not found for higher grade prostate cancer in black men. No significant racial differences were found in S phase fractions, p53 or bcl-2 immunopositivity. However, for prostate cancer in black men there was a significant association between bcl-2 immunopositivity and higher S-phase fractions.

CONCLUSIONS

The aggressive prostate cancers of black men may be characterized by the 2 features of high proliferation and a block to programmed cell death.

Proliferative index determination in prostatic carcinoma tissue: is there any additional prognostic value greater than that of Gleason score, ploidy and pathological stage?

PURPOSE

The proliferative index was evaluated as an additional prognostic variable in 244 radical prostatectomy specimens from patients with prostate cancer. This study was done on the grounds that this variable has shown some promise as a prognostic tool in some other carcinomas, for example breast cancer.

MATERIALS AND METHODS

The proliferative index was evaluated in 244 patients undergoing radical prostatectomy for clinically localized disease between January 1988 and August 1994. Proliferative index was determined using the Ki-67 antibody on fresh frozen tissue and MIB-1 on paraffin embedded tissues. Patients were divided into 2 groups based on a proliferative index of less than 1 (185) or 1 or greater (59). Of the patients 49 (20%) had biochemical failure (median 23 months to progressive prostate specific antigen elevation of 0.5 ng./ml. or more). Those whose treatment failed were also divided into 2 groups according to proliferative index: 32 of 185 (18%) with an index of less than 1 and 17 of 59 (27%) with an index of 1 or more. Gleason score and deoxyribonucleic acid ploidy status were also evaluated in all patients and compared in multivariate regression analysis. Operative specimens were categorized as organ confined, specimen confined or margin positive.

RESULTS

The distribution according to margin status in the 2 groups (proliferative index less than 1 and 1 or more) was 40 versus 60% for organ confined, 67 versus 33% for specimen confined and 72 versus 28% for margin positive disease, respectively. The distribution of time to treatment failure in the 2 groups was not markedly different: 7.2 versus 9.4 months for margin positive, 10 versus 14.5 months for specimen confined and 8.5 versus 12 months for organ confined cancer, respectively.

CONCLUSIONS

Multivariate analysis demonstrated that, although deoxyribonucleic acid ploidy seemed to correlate with more advanced disease, only Gleason sum and pathological T stage reached statistical significance when evaluated against time to treatment failure. A high proliferative index added little above the more traditional prognostic indicators of Gleason score, pathological stage and ploidy. Therefore, we question the value of proliferative index as a prognostic indicator using the aforementioned methodology in prostate cancer.

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.

Racial differences in adenocarcinoma of the prostate in North American men

Black men represent a particularly high risk group for the development of prostate cancer. Current recommendations are that all men over age 50 be screened for prostate cancer annually with a digital rectal examination (DRE) and PSA. Moreover, it has been recommended that men in high risk groups, including blacks and men with a family history of prostate cancer, be screened at an earlier age. At the present time, no adequately performed prospective study has demonstrated a reduction in mortality rate attributable to annual prostate cancer screening. Preliminary reports have suggested that the proportion of men with organ confined tumors increases with PSA based screening, and that a reduction in prostate cancer mortality via screening is feasible. In light of these preliminary studies, increased efforts toward patient awareness and PSA screening are certainly warranted in the black community. Hopefully the result of such programs would be to increase the percentage of black men diagnosed with organ confined prostate cancer. However, the etiology of these striking racial differences remains to be defined. To date no consistent data have been presented which can explain these observations. It is likely that multiple factors will be involved including socioeconomic, environmental, dietary, and genetic. Lastly, little is known of the molecular genetic factors, tumor suppressor genes and/or oncogenes, that play a role in prostate cancer in black men. Increased research efforts are needed in order to understand this problem at the molecular level.

Prognostic value of deoxyribonucleic acid content in prostate cancer: a review of current results

A total of 115 articles on prostate cancer were reviewed for data on the prognostic value of DNA content in the tumor cells. In 44 series, data pertinent to this review were found. There was no consensus in the literature with respect to methods of analysis of DNA content or definitions of subclasses of DNA content such as categories of ploidy. The DNA content of prostate cancer cells was strongly related to tumor grade and stage. When analyzed as a single parameter in univariate analyses, the DNA content had a prognostic value with respect to overall or disease-specific survival. In multivariate analyses the additional prognostic value of the DNA content was less convincing when analysed with tumor grade and stage. The prognostic data from univariate and multivariate analyses available in the literature were mainly derived from patients with advanced disease and data on localized, potentially curable disease were scanty and conflicting.