Intratumoral DNA heterogeneity correlated with lymph node involvement and surgical staging in epithelial ovarian cancer by flow cytometry

Gene expression in epithelial ovarian cancer: a study of intratumor heterogeneity

The aim of this study was to investigate the intratumor heterogeneity of gene expression profiles in epithelial ovarian cancer (EOC). This was done to evaluate whether sampling of a single macrodissected tissue sample from each EOC case would bias the data and result in, eg, prognostic studies based on gene expression microarray experiments. From nine EOCs removed at Odense University Hospital, Denmark, three tumor samples of 200-300 mg each were taken with greatest possible mutual distance. The samples were immediately flash frozen. A parallel section was taken for histopathologic comparison. RNA was extracted from the tissue samples. Five micrograms of each RNA sample was used for labeling. The fragmented biotin-labeled complementary RNA was hybridized to Affymetrix GeneChip Human Genome U133 plus 2.0 arrays, and scanning was performed on the GeneArray scanner 3000 (Affymetrix, Santa Clara, CA). Data were evaluated using hierarchical clustering and intraclass correlation coefficient (ICC) from reliability analysis. All evaluation methods revealed low intratumor heterogeneity. Intratumor ICCs ranged from 0.888 to 0.978. In contrast, "between-tumor" ICC was 0.549 indicating much lower intra- than intertumor heterogeneity. Due to a low degree of intratumor variation, we conclude that it is sufficiently accurate in a clinical setup to use single, macrodissected tumor samples in the evaluation of gene expression in EOCs.

DNA content heterogeneity in neuroblastoma analyzed by means of image cytometry and its potential significance

The aim of this study was to determine the frequency and significance of the tumor DNA content heterogeneity in 33 previously untreated human neuroblastomas. We used image cytometry to selectively analyze neuroblasts by excluding karyorrhectic or stromal cells from cytometric measurements. DNA content heterogeneity with more than one clonal subpopulation on DNA histogram was found in 8 of 33 cases. Of these 8 cases, 4 showed MYCN amplification. Double labeling fluorescent in situ hybridization with probes for the centromeric region of chromosome 2 and MYCN gene was used to confirm the DNA content heterogeneity. DNA content heterogeneity was associated with poorer prognosis in this study (P<0.05). There was a significant correlation between euploidy (di- and tetraploidy) and worse prognosis, but only when heterogeneous neuroblastomas with euploid cell population were assigned to euploid tumors (P=0.006). Our results may explain the conflicting data in the literature regarding ploidy and suggest that DNA content heterogeneity and the presence of a euploid population may predict worse prognosis in neuroblastoma patients.

Cell Proliferation in Ovarian Carcinoma: Superior Accuracy of S-Phase Fraction (SPF) by DNA Labeling Index versus Flow Cytometric SPF, Lack of Independent Prognostic Power for SPF and DNA Ploidy, and Limited Effect of SPF on Tumor Growth Rate

OBJECTIVES

The goal of this work was to test the hypotheses that S-phase fraction (SPF) by DNA labeling index (SPF-LI) would predict the course of the disease for ovarian/peritoneal carcinomas and that SPF-LI would correlate better with pathologic classification and outcome than SPF by DNA flow cytometry (SPF-F).

METHODS

Tritiated thymidine (1985-1988) and bromodeoxyuridine (1988-1999) DNA labeling (SPF-LI) was evaluated in vitro on 178 tumors. Cellular DNA and SPF-F were measured flow cytometrically. During this time, 90% of ovarian/peritoneal tumors accessioned in surgical pathology were studied.

RESULTS

Tumors of low malignant potential (LMP, "borderline") had low SPF-LI (median = 1.2%). High-grade invasive carcinomas of various types and carcinosarcomas all had high SPF-LI (medians = 11.2-23.4%). Serous low-grade invasive carcinomas (median = 1.05) resembled LMP tumors. SPF-LI of ovarian carcinomas other than LMP tumors increased slightly as FIGO stage increased (P = 0.07). Survival of patients with high-grade ovarian carcinomas was not predicted by SPF-LI or SPF-F, nor was DNA ploidy predictive. SPF-LI produced tighter distributions for various tumor types than did SPF-F. Neither SPF nor DNA ploidy contributed to prediction of outcome when tumor type and stage were included in multivariate models. We calculated the mean cell loss rate of high-grade carcinomas to be 94%.

CONCLUSIONS

LMP ovarian/peritoneal tumors have low proliferation rates in contrast to high-grade carcinomas. Proliferation correlated with tumor type and stage, but neither it nor DNA ploidy predicted survival independently. Proliferation rate is growth limiting only when low. At higher levels cell loss limits growth. SPF-LI measures proliferation more accurately than SPF-F; SPF-F is not sufficiently reliable for clinical use.

Intratumoral heterogeneity of DNA content in renal cell carcinoma and its prognostic significance

BACKGROUND

A multiple sampling study was performed on 124 specimens of renal cell carcinomas to analyze the consistency and reliability of DNA measurements. The authors investigated intratumoral DNA heterogeneity and its role as a adverse prognostic factor for disease progression.

METHODS

DNA content was analyzed by flow cytometry on three different samples of the same tumor. The Cronbach alpha coefficient was used to assess the reliability and a Cox proportional hazards model was used to test the effect of DNA ploidy heterogeneity on time of disease progression.

RESULTS

The agreement among the DNA ploidy samples was high. The number of aneuploid findings increased significantly with the number of samples analyzed. The presence of non-diploid cell populations was a significant adverse predictive value for disease progression. However, the authors were unable to demonstrate that intratumoral heterogeneity DNA content had any influence on the biological behavior of the tumor.

CONCLUSIONS

Determination of DNA ploidy based on single samples may be inaccurate. Spatial variation in DNA ploidy is a feature of renal cell carcinoma; however, its biologic significance remains to be demonstrated.

Huge fetal sacrococcygeal teratoma with a completely formed eye and intratumoral DNA ploidy heterogeneity

Preterm infants and newborns with sacrococcygeal teratomas are at high risk for prenatal and perinatal complications. The prognosis depends on size and histology of the tumor, degree of prematurity, associated malformations, route of delivery, and prompt and complete surgical removal. Virtually any tissue can be present in a sacrococcygeal teratoma, but to date, ocular lens has been documented only as lentinoids (lens-like cells), whereas flow-cytometric data have been variably interpreted. We describe a case of a sacrococcygeal teratoma in an infant of 29 weeks gestational age that is remarkable for the weight (4500 g), the presence of a completely formed eye, and intratumoral DNA ploidy heterogeneity.

The cellular basis of tumor progression

Variability in disease presentation and course is a hallmark of cancer. Variability is seen among similarly diagnosed cancers in different patients or animal hosts and in the same cancer at different periods of time. This latter type of variability, termed "tumor progression," was defined by Foulds in a series of six rules that describe the independent behavior of individual cancers and the independent evolution of different cancer characteristics. Tumor progression is believed to result from variability among subpopulations of tumor cells within individual cancers and from selection of these subpopulations by conditions within the cancer environment, such that different subpopulations come to prominence over the course of cancer development and growth. Interactions among subpopulations, however, modulate tumor behavior as well as tumor evolution. The leading hypothesis for the origin of tumor subpopulations is the genetic instability of cancer cells. There are a number of possible mechanisms of genetic instability, some internal to cancer cells (mutation, amplification, mutator phenotypes, DNA repair deficiencies) and some present in the tumor microenvironment (endogenous mutagens). There are also potential epigenetic mechanisms of variability, including alterations in gene regulation, differentiation, adaptation, and cell fusion. Regardless of mechanism, the heterogeneity of tumor subpopulations poses a number of challenges to the practice of cancer research, including the design of reproducible and meaningful experiments. Tumor heterogeneity also has significant consequences for the clinical assessment of tumor prognosis and the development of effective treatment regimens.

Flow cytometric analysis of lymph node metastases in advanced ovarian cancer: clinical and biologic significance

OBJECTIVE

This study was undertaken to evaluate the deoxyribonucleic acid content and S-phase fraction in advanced epithelial ovarian carcinomas to determine whether lymph node metastases are biologically distinct from peritoneal sites of metastases.

STUDY DESIGN

Thirty-five patients with stage III or IV epithelial ovarian cancer who had undergone complete pelvic and paraaortic lymphadenectomy had representative samples from the primary ovarian tumor, peritoneal metastases, and lymph node metastases analyzed by flow cytometry for deoxyribonucleic acid nuclear content and S-phase fraction.

RESULTS

Diploid cell lines are found in metastatic lymph nodes (52%) significantly more frequently than in peritoneal metastases (25%, p < 0.02) or in primary ovarian tumors (26%, p < 0.001). The ploidy category frequency distribution of peritoneal metastases mirrors that found in the primary tumor, and both are significantly different from the ploidy category frequency distribution found in metastatic lymph nodes. Heterogeneity among sites is common, being identified in 54% of patients. Peritoneal metastases are more likely to be concordant with the primary tumor (69%) than are lymph node metastases (39%, p < 0.001). Mean S-phase fraction did not differ overall by site but was significantly different between diploid and aneuploid samples by site. Diploid lymph node metastases were found to have the lowest mean S-phase fraction (7.2% +/- 3.3%), and aneuploid lymph node metastases had the highest mean S-phase fraction (22.3% +/- 10.2%). Diploidy of the primary tumor is a positive predictor of long-term survival. Tumoral heterogeneity and lymph node metastases are not related to survival in this group of patients who underwent therapeutic pelvic and aortic lymphadenectomy.

CONCLUSIONS

A high proportion of tumor deposits found in metastatic lymph nodes are diploid with a low S-phase fraction. Therapeutic pelvic and aortic lymph node dissection removes disease that, on the basis of flow cytometric characteristics, may be predicted to be resistant to chemotherapy and radiation therapy.

Interphase karyotypic analysis of chromosomes 11, 17 and X in invasive squamous-cell carcinoma of the cervix: morphological correlation with HPV infection

Human papillomavirus (HPV) infection has been widely implicated in cervical carcinogenesis, but it appears to be an early event, with other genetic abnormalities being required for biological transformation. In this study, interphase cytogenetic analysis of numerical abnormalities of chromosomes 11, 17 and X was performed on paraffin-embedded tissue sections from 25 invasive squamous-cell carcinomas of the cervix and compared with both histopathological features and the morphological distribution of HPV sequences as determined by in situ hybridisation. Numerical differences between chromosomes were identified in 76% of cases, with underrepresentation of chromosomes 11 and/or 17 relative to X in 64% of the total; 22 of 25 cases were HPV-positive, containing either HPV 16, 18 or 31. There was no relationship between the distribution of viral sequences and chromosomal pattern, suggesting that HPV infection precedes karyotypic changes. Our findings suggest that relative reduction in number of chromosomes 11 and 17 is important in the development of invasive cervical neoplasia and are consistent with the putative presence of relevant tumour-suppressor genes on these chromosomes.

Value of quantitative pathological variables as prognostic factors in advanced ovarian carcinoma

AIMS

To evaluate correlations among clinical, pathological, morphometric, stereological, and DNA flow cytometric variables and their prognostic value in advanced ovarian cancer.

METHODS

Tissue was collected from 180 patients with advanced ovarian cancer. All 180 had undergone debulking surgery and were being treated with cisplatin. Long term follow up was available for all patients. The mitotic activity index (MAI), volume % of epithelium (VPE), mean nuclear area (MNA), standard deviation of the nuclear area (SDNA), estimates of volume weighted mean nuclear volume (nu v), and variables obtained from minimum spanning tree (MST) analysis were assessed in the least differentiated tumour section in each case. DNA flow cytometry was also performed.

RESULTS

Quantitative pathological features differed significantly with respect to histological grade. The MAI, MNA, SDNA, and the number of points connected to three neighbours differed significantly among the different DNA ploidy groups. The VPE and number of points connected to two or three neighbours differed significantly between FIGO stages III and IV. Fifty two (29%) patients survived. FIGO stage, residual disease and SDNA had prognostic significance on both univariate and multivariate survival analysis. In patients with FIGO III stage disease and residual tumour nodes < or = 2 cm in diameter (67 patients, 29 (43%) survivors) a prognostic index was established based on SDNA and of the line length of the MST. The median survival time was not reached in a subgroup of patients with favourable prognosis (overall survival 57%). Median survival was 32 months for patients with an unfavourable index score (overall survival 28%).

CONCLUSION

Morphometric variables have important additional value in predicting prognosis in patients with advanced ovarian cancer.