Clinical applications of DNA content parameters in patients with squamous cell carcinomas of the head and neck.
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Publications and source records attributed to Z Maciorowski.
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BACKGROUND: DNA ploidy analysis has been investigated as a prognostic indicator in prostate cancer. Most of the data is derived from retrospective studies using paraffin-embedded tissue. This method has drawbacks related to the quality of DNA histograms and uncontrolled data collection. METHODS: DNA ploidy analysis of freshly resected prostatic tissue was prospectively compared with conventional prognostic variables in 97 men treated with radical prostatectomy for localized prostate cancer. RESULTS: Regarding the patients, 31.9% were African American and 66% had pathologic Stages C or D1 disease. Only 9.6% of patients with Stages A2 and B had a prostate-specific antigen (PSA) value greater than 10 ng/ml, whereas 97% of patients with PSA values greater than 20 ng/ml had pathologic Stages C and D1. PSA levels correlated with Gleason score (P = < 0.05); 51% and 100% of patients with Gleason score 5-7 and 8-10, respectively, had PSA values greater than 10 ng/ml. Twenty-two patients (23%) had DNA aneuploid tumors. Comparisons of mechanical to enzymatic cell suspensions indicated that DNA aneuploidy was better preserved in mechanical cell preparations. DNA ploidy correlated with pathologic stage (P = < 0.05) and Gleason score (P = < 0.05). Fifteen of 79 patients (18.9%) with Gleason score 5-7 had DNA aneuploid tumors versus 71.4% of patients with Gleason score 8-10. PSA groups correlated with ploidy status (P = 0.01). Although the majority of patients (19 of 22) with DNA aneuploid tumors had elevated preoperative PSA levels, none had a PSA value greater than 50 ng/ml. CONCLUSIONS: DNA ploidy analysis correlated with established prognostic indicators in prostate cancer; however, its independent correlation with natural history and treatment outcome must be established for it to have an effect on therapeutic decisions.
DNA content analysis of formalin fixed paraffin embedded (FFPE) tissue permits determination of the influence of DNA content on the prognosis in cohorts of patients for whom the clinical outcome is known. Of key importance in such an analysis is the accuracy of DNA content determination. Variations in the quality of DNA histograms from FFPE tissues of different types prompted a comparative evaluation of the preparative methodology of FFPE soft tissue sarcomas for DNA flow cytometry. Following deparaffination and rehydration of fixed tissue, and prior to fluorochrome staining, tissue blocks of 15 DNA aneuploid soft tissue sarcomas were subjected to repeated experimental (time x concentration) enzyme exposures. The goal of these studies was to define the optimal tissue specific retrieval technique with the coefficient of variation, maintenance of DNA aneuploidy, and DNA index as endpoints. After optimizing the technique, the DNA content of 50 soft tissue neoplasms derived from FFPE specimens was compared to the corresponding fresh surgical tissue. The observed 14 percent error rate in the determination of DNA ploidy status suggest limited utility for FFPE tissue in prospective therapeutic trials of soft tissue sarcoma.
Experimental research involving human solid tumors often requires single cell suspensions of high yield that are representative of the tissue of origin and in which the cellular property of interest is preserved. This is particularly necessary for the determination of DNA ploidy by flow cytometry. Mechanical dissaggregation and proteolytic enzyme digestion are the most commonly employed dissociation techniques for solid tumors. Comparative testing of techniques is often not performed. Mechanical and proteolytic enzyme dissociation techniques were comparatively tested in 77 human squamous cell cancers of the head and neck (SCCHN) and 25 human colon cancers for cellular yield, dye exclusion viability, quality, and morphology of DNA histograms, and the presence and proportion of DNA aneuploid subpopulations. Significant and consistent DNA aneuploid subpopulation losses were noted in mechanical preparations of SCCHN and enzymatic preparations of colon cancers. The frequency of SCCHN specimens with DNA aneuploid subpopulations was underestimated by 52% in mechanical cell suspensions, and the proportion of DNA aneuploid cells was diminished in an additional 30% of the specimens. Conversely, the frequency of specimens with DNA aneuploid subpopulations was underestimated by 38% in cell suspensions from enzymatically dissociated human colon cancer and their proportion diminished in an additional 50% of the specimens. Incubations of human colon cancers with three commonly employed proteolytic enzymes demonstrated a progressive loss of DNA aneuploid subpopulations as a function of enzyme concentration and incubation time. This is a serious potential source of error in the flow cytometric determination of DNA ploidy in human solid tumors, and may contribute to the diversity of results obtained and occasional contradictory conclusions reached in such studies.
Data regarding DNA content parameters in soft tissue sarcoma is limited. Development and optimization of tissue specific preparative techniques for DNA flow cytometry was undertaken prior to routine DNA content analysis of soft tissue neoplasms; 154 soft tissue tumors were studied. Dissociation dependent differences in cellular yields, viabilities, maintenance of DNA aneuploid populations, coefficients of variation, and DNA index supported the need for these developmental studies. Fifty-six of eighty-nine patients had DNA aneuploid soft tissue sarcomas. A relationship between DNA aneuploidy and grade was seen in this series with 38% with low grade, 59% with moderate grade, and 69% with high grade tumors demonstrating DNA aneuploid populations (P < 0.005). The mean S-phase fraction for DNA diploid and aneuploid sarcomas was 7.2% and 13.3%, respectively (P < 0.001). When classified by histologic grade of the primary tumor, a greater percentage of metastatic lesions were DNA aneuploid (4 of 7 grade 2 lesions, and 15 of 16 grade 3 lesions). Decreases in cellular yields and rate of DNA aneuploidy were observed in a subgroup of patients with localized high grade sarcoma treated preoperatively, as compared to patients treated with initial surgery. Prospective correlation of DNA content parameters to prognosis and response to cytotoxic therapy are now possible and are ongoing.
Regional metastases are a major determinant in the treatment outcome of patients with squamous cell carcinoma of the head and neck. Metastases do not respond as well to cytotoxic therapy as do primary tumors. DNA diploid tumors or tumor components also respond poorly to intermittent cytotoxic therapy. In our series of 497 patients with squamous cell carcinoma of the head and neck, the percentage of pure DNA diploid tumors and the mean DNA indexes in 497 primary tumors and 82 regional metastases were 34% and 1.54 and 50% and 1.34, respectively. Paired comparisons were performed in 61 patients and revealed a statistically significant increase in the frequency of DNA diploid tumors (27.4% to 41.2%) in associated lymph node metastases. The clinical observation that patients with squamous cell carcinoma of the head and neck and regional lymph node metastases have a poorer prognosis and a poorer response to cytotoxic therapy may in part be explained by the increased incidence of DNA diploid tumors in their regional lymph nodes, and the poorer response of such tumors to cytotoxic therapy.
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The presence and degree of DNA aneuploidy as measured by the DNA index (DI) and the S phase fraction (SPF) were determined by flow cytometry in 294 specimens from 237 patients with untreated and recurrent squamous cell carcinomas of the head and neck (SCCHN). A descriptive analysis was performed in which the specimen DNA parameters were correlated with stage, size of primary, degree of lymph node involvement, morphological grade, and treatment status of the corresponding patients. Approximately 70% of the previously untreated specimens contained DNA aneuploid populations (DI greater than 1.10) and three quarters had SPF that were above 15%. There was a strong, direct association between DI and SPF (P less than 0.001). There was no correlation of the presence or degree of DNA aneuploidy with the stage of the tumor or the size of the primary or conventional morphological grade of the tumor. Specimens from patients with recurrent tumors and untreated patients with N3 lymph nodes had significantly lower rates of DNA aneuploidy and mean DI. Serial determinations of DNA aneuploidy in patients with SCCHN undergoing cytotoxic therapy are ongoing and may prove useful in the identification and understanding of resistance and response in this tumor.
The application of flow cytometry (FCM) to solid human tumors has been hindered by the difficulty in producing high yield, viable, unaltered single cell suspensions. Carcinomas containing a high desmosomal content, such as well-differentiated squamous cell (SCC) cancers of the head and neck (H&N) region, are particularly difficult to prepare. The desire to employ FCM to study cellular DNA parameters of these tumors led to the use of a 3-methylcholanthrene induced murine SCC for the comparative testing of preparative techniques. Dissociation techniques, including mechanical, enucleation, chemical, single and combination enzymes methods, were comparatively tested. Of these, the combination enzyme treatment employing trypsin and collagenase produced the highest cell yields in the shortest time with the highest dye exclusion viability and the least expense. Several fixation systems including glutaraldehyde, paraformaldehyde, acetic acid, and ethanol were comparatively tested using percent of cell loss and quality of the DNA histograms produced as end points. Ethanol-water systems with added fetal calf serum provided minimal cell loss and high quality histograms which were stable for extended periods of time. A murine tumor, closely mimicking the histology of the human tumor of interest, may be used as a model for the determination of optimum techniques of solid tumor preparation for flow cytometric analysis.
Intense interest in advanced squamous cell cancers of the head and neck (SCC of H&N) has resulted from the recent progress made in tumor responses with chemotherapy and radiotherapy. Unfortunately, the response patterns and clinical outcome of such patients are not adequately predicted on an individual patient basis using clinical parameters or conventional morphology. The study of flow cytometrically determined cellular parameters in such tumors is therefore of interest, but is hindered by inadequate tumor preparative technology. The previous article (10) in this journal describes the use of a murine SCC tumor, LC12, which was employed for comparative testing and determination of optimum techniques of preparation for this tumor. This report describes the application of these techniques to 144 specimens of human SCC of H&N. The mean total yield for these specimens is 7.4 X 10(7) cells/g of tissue. The mean viable enzymatic yield (3.3 X 10(7) cells/g) was higher than the mean viable mechanical yield (2.0 X 10(7) cells/g) except when lymph nodes were the source of the specimen (5.4 X 10(7) cells/g). The mean dye exclusion viability from enzymatically dissociated specimens were above 90%. Significant aneuploidal subpopulation losses were evident in mechanically dissociated and enucleated specimens. 65% of the enzymatically dissociated specimens were successfully cultured with a mean cloning efficiency of 2.1 X 10(-3). Preparative techniques derived from comparative testing with a murine standard tumor have been successfully applied to 144 specimens of SCC of H&N with resultant high yields and excellent viability. Technical problems detected during the preliminary testing with LC12 were confirmed in the human tumors.
Estrogen receptor (ER) determinations were performed on cytosol preparations of Ficoll-Hypaque density separated mononuclear cells from 11 patients with chronic lymphocytic leukemia (CLL). The presence of ER was noted in 8 of 11 specimens (73%). ER ranged from 431 fmole/mg to 4.3 fmole/mg cytosol protein. Two types of receptor subunits were observed at the 8S and 4S region of the sucrose gradient. In addition, 1 of 3 Epstein-Barr virus (EBV) transformed B-lymphoblastoid cell lines from healthy donors had a measurable amount of ER. Patient R.L., who was refractory to standard chemotherapy and radiation and was ER positive, experienced a minor response to Tamoxifen therapy, with subsequent loss of ER. The demonstration of ER in CLL suggests that this malignancy may have a hormone-dependent subpopulation of cells.
We have demonstrated that human tumors can be labelled efficiently with the 111indium-oxine chelate. Subsequently, this isotope can be released by cytotoxic lymphoid cells. Both natural and induced cytotoxicity can be demonstrated utilizing this isotope release method. Because of the slow spontaneous release of 111indium and its efficient labelling of human tumor cells, this isotope release assay can be utilized in long-term cytotoxic assays in the study of human tumor immunology.