DNA content of head and neck squamous carcinoma by flow and image cytometry

Chromosomal instability, aneuploidy and routine high-resolution DNA content analysis in oral cancer risk evaluation

Carcinogen exposure of the oral cavity is thought to create an extensive 'field cancerization'. According to this model, a very early precursor of oral cancer is a patch of normal-appearing mucosa in which stem cells share genetic/genomic aberrations. These precancerous fields then become clinically visible as white and red lesions (leuko- and erythro-plakias), which represent the vast majority of the oral potentially malignant disorders. This review focuses on aneuploidy (where it is from) and on biomarkers associated with DNA aneuploidy in oral mucosa and oral potentially malignant disorders, as detected by DNA image and flow cytometry. Data from the literature strongly support the association of DNA ploidy with dysplasia. However, work is still needed to prove the clinical value of DNA ploidy in large-scale prospective studies. Using high-resolution DNA flow cytometry with fresh/frozen material and the degree of DNA aneuploidy (DNA Index) might improve the prediction of risk of oral cancer development.

Evaluation of nuclear morphometry and DNA ploidy status for detection of malignant and premalignant oral lesions: quantitative cytologic assessment and review of methods for cytomorphometric measurements

PURPOSE

Detection of a precancerous or cancerous lesion when small is one of the most important factors to improve 5-year survival rates of oral cancer. Although surgical biopsy is the most definitive method for diagnosing oral lesions, it is impractical to routinely subject large numbers of patients to biopsy. Recently, cytomorphometric assessments improved by advanced computer-assisted image analysis systems have gained importance. This study was established to evaluate the efficacy of nuclear cytomorphometric analysis and DNA ploidy status for the detection of oral malignancies. Methods used for cytomorphometric analysis were also reviewed.

PATIENTS AND METHODS

Oral mucosal smears (n = 44) were obtained from patients (n = 22) presenting with various oral lesions using a cytobrush immediately before biopsy. Cytomorphometric measurements and nuclear Feulgen DNA content analysis were carried out after the Feulgen staining procedure. Smears from the lesion site constituted the study group whereas contralateral healthy mucosal sites served as control.

RESULTS

DNA ploidy analysis revealed 20 diploid (90.9%) and 2 aneuploid DNA patterns (9.1%) sampled from the lateral margin of the tongue and floor of the mouth. When only malignant lesions were considered, aneuploidy rate was 16.7% whereas a diploid pattern was indicated for 83.3% of the sample. With cytomorphometric measurements, a statistically significant difference was shown for nuclear perimeter, area, diameter equivalent to circle, minimum and maximum Feret, intensity, DNA content (c) and DNA index values.

CONCLUSIONS

Cytomorphometric analysis via oral brush biopsy is a valuable adjunct to biopsy for identification of premalignant and early stage cancerous oral lesions as a rapid and minimally invasive procedure with high specificity and sensitivity rates, requiring no topical or local anesthetic.

Heterogeneity, histological features and DNA ploidy in oral carcinoma by image-based analysis

Oral squamous carcinomas appear heterogeneous on DNA ploidy analysis. However, this may be partly a result of sample dilution or the detection limit of techniques. The aim of this study was to determine whether oral squamous carcinomas are heterogeneous for ploidy status using image-based ploidy analysis and to determine whether ploidy status correlates with histological parameters. Multiple samples from 42 oral squamous carcinomas were analysed for DNA ploidy using an image-based system and scored for histological parameters. 22 were uniformly aneuploid, 1 uniformly tetraploid and 3 uniformly diploid. 16 appeared heterogeneous but only 8 appeared to be genuinely heterogeneous when minor ploidy histogram peaks were taken into account. Ploidy was closely related to nuclear pleomorphism but not differentiation. Sample variation, detection limits and diagnostic criteria account for much of the ploidy heterogeneity observed. Confident diagnosis of diploid status in an oral squamous cell carcinoma requires a minimum of 5 samples.

DNA ploidy, S-phase fraction and associations with 2-18F-fluoro-deoxy-2-D-glucose positron emission tomography findings before and during therapy of head and neck squamous cell carcinoma

OBJECTIVES

The main purpose of this study was to investigate the feasibility of fine needle aspiration (FNA) of neck node metastases in head and neck squamous cell carcinoma (HNSCC) for evaluating changes in DNA ploidy and S-phase fraction (SPF) during cytotoxic treatment. The results of flow cytometric (FCM) and image cytometric (ICM) analyses of ploidy were compared. Secondly, the association of SPF and ploidy with the metabolic rate (MR) of 2-18F-fluoro-deoxy-2-D-glucose (FDG) in positron emission tomography (PET) was studied.

MATERIAL AND METHODS

Between 1993 and 1999, 47 patients with locally advanced, non-resectable HNSCC underwent FDG PET prior to (PET1) and early during (PET2) cytotoxic radical treatment. The MR of FDG was calculated separately in primary tumours and lymph node metastases. Immediately after both PET scans, FNA of node metastases was done in 29 patients at PET1 and in 27 at PET2. DNA ploidy was evaluated using FCM and manually using ICM. The SPF was evaluated using FCM only.

RESULTS

At PET1 it was possible to evaluate the SPF using FCM in only 13/29 aspirations due to a poor cell yield or large amounts of debris. Ploidy was obtained in 23/29 aspirates using FCM and in 27/29 using ICM. A discordance in ploidy findings was apparent, with more non-diploid clones being detected by ICM than FCM. Eradication of non-diploid clones during therapy was observed in six cases using FCM, of which only one was confirmed by ICM. Neither SPF nor ploidy status showed any strong correlation with the MR of FDG.

CONCLUSION

FNA of HNSCC metastases demands a high and qualitatively good cell yield for FCM examinations. ICM is laborious but feasible and offers more accurate detection of non-diploid cell clones. Ploidy and SPF were not strongly associated with FDG metabolism.

Larynx squamous cell carcinoma: concepts and future directions

The larynx is one of the most important structures in the upper aerodigestive tract. Functional impairment of the larynx is a bur-den to patients who suffer from laryngeal carcinoma, the second most common cancer of the head and neck region after the oral cavity.

Cell proliferation activity and kinetic profile in the prognosis and therapeutic management of carcinoma of the pharynx and larynx

Prognosis and management of carcinoma of the pharynx and larynx is now based on the morphologic analysis of the tumor spreading, differentiation grading, and type of microscopic invasion. The DNA ploidy status and the cell proliferation activity analyzed by flow cytometry give us complementary information about the prognosis and the management and support of the patients. We performed a study of 91 cases of carcinoma of the larynx and pharynx by means of flow cytometry. Forty-three patients were treated by surgery alone, and 48 patients also received radiotherapy. Fifty-five were aneuploid (60%); this percentage increased to 74% in the pharynx area and fell to 47% at the larynx level. The aneuploid tumors showed worse behavior in the patients treated by surgery alone compared with those who also received radiotherapy. The S-phase fraction was high in aneuploid tumors, in positive lymph nodes, and in advanced stages. The S-phase fraction was higher in poorly differentiated tumors. In patients treated by surgery alone, we noticed that by combining both cytometric variables two different kinetic profiles could be defined related to the patients' behavior. The diploid tumors with a low S phase had the greatest rates of survival, whereas diploid tumors with a high rate of S phase and aneuploids had a lower rate.

DNA ploidy and cell cycle distribution of breast cancer aspirate cells measured by image cytometry and analyzed by artificial neural networks for their prognostic significance

Chromosomal abnormalities are commonly associated with cancer, and their importance in the pathogenesis of the disease has been well recognized. Also recognized in recent years is the possibility that, together with chromosomal abnormalities, DNA ploidy of breast cancer aspirate cells, measured by image cytometric techniques, may correlate with prognosis of the disease. Here, we have examined the use of an artificial neural network to predict: 1) subclinical metastatic disease in the regional lymph nodes and 2) histological assessment, through the analysis of data obtained by image cytometric techniques of fine needle aspirates of breast tumors. The cellular features considered were: 1) DNA ploidy measured in terms of nuclear DNA content as well as by cell cycle distribution; 2) size of the S-phase fraction; and 3) nuclear pleomorphism. A further objective of the study was to analyze individual markers in terms of impact significance on predicting outcome in both cases. DNA ploidy, indicated by cell cycle distribution, was found markedly to influence the prediction of nodal spread of breast cancer, and nuclear pleomorphism to a lesser degree. Furthermore, a comparison between histological assessment and artificial neural network prediction shows a closer correlation between the neural approach and the development of further metastases as indicated in subsequent follow-up, than does histological assessment. These data demonstrate that artificial neural networks are capable of providing powerful and reliable indicators of possible lymph node metastasis, using measurements of cellular features alone.

Assessing the patient at risk for oral squamous cell carcinoma

Patients and health care workers require continuing education to promote knowledge of the signs, symptoms, and risk factors for oral cancer. This paper reviews the literature assessing diagnostic tools that are currently available or being developed, in order to assist in the biopsy site selection and subsequent diagnosis of patients at risk for oral cancer. There is a general consensus that oral examination of patients at risk for oral squamous cell carcinoma (SCC) should be conducted on a routine basis. However, there can be false-positive and false-negative findings. Toluidine blue has been shown to be useful as an adjunct to the clinical examination when used by experienced clinicians. Exfoliative cytology is not currently used as a routine measure for the evaluation of lesions of the oral mucosa, but further development and the application of biologic markers to cytologic specimens may increase its value. Fluorescent imaging of malignant lesions of the oral mucosa has been shown to be sensitive and specific in animal models but thus far has been reported in only one human trial. The sensitivity and specificity of these techniques when used by general practitioners need to be assessed. Further, none of the above procedures has yet been shown to be a cost-effective public health measure in screening for oral cancer.

DNA analysis of squamous cell carcinoma in the oral cavity by image cytometry and its rating in the assessment of tumor prognosis

Image cytometric measurements on the DNA content of squamous cell carcinoma of the oral cavity were carried out to evaluate its relationship with clinicopathological features. In the prospective study 52 patients with operable oral cavity carcinoma in stage T1-4 and N0-3 were studied. The tumors were classified according to the TNM classification (UICC 1987) and graded histopathologically. A positive correlation between tumor size and ploidy status was observed. There was a significant correlation between ploidy status and histologically confirmed cervical lymph node metastases (P < 0.03). A relationship between histopathological grading and ploidy status was not found. The cumulative 5-year survival rate was significantly higher (P < 0.03) among patients with diploid DNA findings than among those with nondiploid findings. When assessing the prognosis of squamous cell carcinoma, DNA cytometry analysis should be used as an additional method. Particularly the primarily existing, significantly higher N stage, a higher frequency of metastases, and a significantly lower survival rate with nondiploid tumors underline the importance of this examination method.

DNA ploidy and protein synthesis in squamous cell carcinoma cell lines of the head and neck

Aneuploidy as abnormal nuclear DNA content, is considered almost positive evidence of malignancy. In this study three diploid and three aneuploid squamous cell carcinoma (SCC) cell lines were examined for DNA content by flow cytometry. The DNA indices of the SCC cell lines were found to range from 1.0 to 2.1. The mitotic activity of the diploid cell lines was 1.6 times higher and the cells were smaller than aneuploid cells. To find a molecular basis for these differences, the pattern of the de-novo synthesized proteins was analyzed by means of [35S]methionine incorporation, electrophoresis, and autoradiography. In all aneuploid SCC cell lines tested in this experiment, the increase of nuclear DNA content is associated with the synthesis of a novel protein with a molecular mass of approximate 55 kDa as well as with altered synthesis rates of two preexisting proteins (50 kDa and 100 kDa). For determination of the amino acid uptake in diploid and aneuploid cells, the accumulation of [35S]methionine was measured as a function of time by liquid scintillation counting. No significant difference was found in the uptake rate between diploid and aneuploid cells with the same protein content. However, discrepancies were revealed when equal numbers of cells with different DNA index were used, suggesting, that protein turnover is different in diploid and aneuploid SCC cells.

DNA ploidy analysis of squamous cell carcinomas of the oral and maxillofacial region: clinical and pathologic correlations

DNA ploidy was investigated in 61 specimens obtained from 25 patients with squamous carcinoma of the oral and maxillofacial region. Biopsy specimens of normal tissue surrounding the tumor were also obtained in six patients. Single-cell suspensions for flow cytometric analysis were prepared. The DNA ploidy and histogram were calculated and compared with the histologic grade, presence of lymph node metastases, and course of the disease. The ploidy of the main stemline was peridiploid in 17 carcinomas, hyperdiploid in three, and aneuploid in five. Histologic grade but not nodal involvement was associated with the ploidy of the main stemline. Of 15 multisampled carcinomas 13 showed constant DNA ploidy and histogram classification. In the other two major changes in DNA ploidy (from peridiploid to hyperdiploid in the first and from peridiploid to aneuploid in the second) were found. Survival information was available for 24 patients. Ploidy values higher or lower than 2.5 c were strongly predictive of both overall (p < 0.001) and relapse-free survival (p < 0.001). The lymph node status proved a powerful prognostic indicator (p = 0.014) but was not related to the relapse-free time of survival. Multiparametric evaluation of survival revealed an independent role of both DNA ploidy and nodal involvement in the prognosis of squamous carcinoma of the oral and maxillofacial region.