Comparative DNA analysis by image cytometry and flow cytometry in non-small cell lung cancer

DNA image cytometric analysis of bronchial washings as an adjunct for the detection of lung cancer in a clinical setting

Background

DNA aneuploidy has a potential to become an adjunct to conventional cytology for diagnosis of lung cancer, but its value in bronchial washings has not been well evaluated.

Methods

We conducted a retrospective study on patients who underwent bronchoscopy and the bronchial washings were submitted for both cytology and DNA image cytometry (DNA‐ICM) examination. The sensitivity and specificity of two methods and both in combination were compared. Analysis of clinical subgroups and DNA histogram were also performed.

Results

The study included 626 patients (326 patients with lung cancer and 300 patients with benign lung diseases). The sensitivity of cytology, DNA‐ICM, and combination test for lung cancer were 53.3%, 62.3%, and 75.8%, respectively, and the sensitivity of DNA‐ICM and combination test were superior to that of cytology (p < 0.05). A modest reduction of specificity was found in DNA‐ICM compared with cytology (91.3% vs. 98.3%, p < 0.05). Subgroup analysis showed there was no significant difference in sensitivity of DNA‐ICM between the visible tumor group and the invisible tumor group (66.5% vs. 56.9%, χ² = 3.114, p = 0.078). Among 101 patients with invisible endobronchial tumor, the positive rates for DNA‐ICM of washing, cytology of washing, brushing and biopsy were 62.4%, 41.6%, 40.6%, and 45.5%, respectively. DNA‐ICM in combination with the basic bronchoscopy techniques could increase the sensitivity from 67.3% to 87.1% (p = 0.000). The DNA histogram analysis showed 25.3% washing samples of lung cancer were diploid pattern, 49.4% were scattered aneuploid cells pattern, and 25.3% were aneuploid peaks pattern. Small cell lung cancer had the highest proportion of aneuploid peaks pattern (p < 0.05).

Conclusions

DNA‐ICM could be used as an adjunct for the detection of lung cancer. The combination of DNA‐ICM and basic bronchoscopy techniques could significantly increase the sensitivity, especially for the patients suspected of peripheral lung cancer, and contribute to select subjects for advanced bronchoscopy.

Nuclear morphometry and ploidy of normal and neoplastic haemocytes in mussels

Haemic neoplasia (HN) in bivalves has been reported in association with mass mortality events in various species of molluscs. The aim of this work was to quantify the nuclear morphometry and DNA content of neoplastic cells of mussels Mytilus galloprovincialis affected by HN using nuclear densitometry in Feulgen-stained preparations. The results were also compared with a population of normal mussel haemocytes. We captured 256 images of 3 different neoplasia stages and 120 images of normal haemocytes; thus, a total of 120,166 nuclei were analysed. We extracted 21 morphological parameters from normal and neoplastic nuclei. Eighteen of these parameters were different (P<0.05). Among those (expressed in pixel units—inter-pixel distance of 0.45 micrometres—as: normal vs. neoplastic) nuclear area (117.1±94.1 vs. 423.1±226.9), perimeter (44.9±14.0 vs. 79.0±21.3) and (IOD) integrated optical density (13.47±34.5 vs. 177.1±150.8) were relevant features to discriminate between normal and neoplastic cells. Those differences allowed identifying two distinctive populations of neoplastic nuclei, occasionally in the same individuals at a given phase of the disease. Moreover, neoplastic haemocytes in less extended lesions showed a ploidy value of 6.2 n along with the presence of a second population of circulating cells with a DNA content of 10.7n. In samples with moderate disease only one peak at 7n was observed. Finally, in more severe conditions, a further ploidy peak of 7.8n was recorded, accompanied by a shallow but broad peak of 31n. This latter extreme value is thought to be due to the presence of giant multinucleated cells where individual nuclei overlap in space and cannot be discerned individually. Computer-based imaging allowed the direct visualization of the cell populations and simultaneous collection of ploidy data as well as morphological features of nuclei.

DNA index determination with Automated Cellular Imaging System (ACIS) in Barrett's esophagus: comparison with CAS 200

Background

For solid tumors, image cytometry has been shown to be more sensitive for diagnosing DNA content abnormalities (aneuploidy) than flow cytometry. Image cytometry has often been performed using the semi-automated CAS 200 system. Recently, an Automated Cellular Imaging System (ACIS) was introduced to determine DNA content (DNA index), but it has not been validated.

Methods

Using the CAS 200 system and ACIS, we compared the DNA index (DI) obtained from the same archived formalin-fixed and paraffin embedded tissue samples from Barrett's esophagus related lesions, including samples with specialized intestinal metaplasia without dysplasia, low-grade dysplasia, high-grade dysplasia and adenocarcinoma.

Results

Although there was a very good correlation between the DI values determined by ACIS and CAS 200, the former was 25% more sensitive in detecting aneuploidy. ACIS yielded a mean DI value 18% higher than that obtained by CAS 200 (p < 0.001; paired t test). In addition, the average time required to perform a DNA ploidy analysis was shorter with the ACIS (30–40 min) than with the CAS 200 (40–70 min). Results obtained by ACIS gave excellent inter-and intra-observer variability (coefficient of correlation >0.9 for both, p < 0.0001).

Conclusion

Compared with the CAS 200, the ACIS is a more sensitive and less time consuming technique for determining DNA ploidy. Results obtained by ACIS are also highly reproducible.

Invasive front in oral squamous cell carcinoma: image and flow cytometric analysis with clinicopathologic correlation

OBJECTIVE

Pathologists have drawn attention to the invasive tumor front (ITF) in the determination of the biologic aggressiveness of oral cancer. We have attempted to discover the prognostic significance of cancer cells with abnormal DNA content at the ITF of oral squamous cell carcinoma.

STUDY DESIGN

A comparative DNA analysis by means of image cytometry and flow cytometry was conducted to confirm the usefulness of image cytometry in detecting cancer cells having abnormal DNA content at the ITF. The prognostic value of cancer cells with abnormal DNA content ws examined by a multivariate analysis for 195 patients with oral squamous cell carcinoma.

RESULTS

In the comparative DNA analysis, it was suggested that image cytometry is useful for detecting cancer cells with abnormal DNA content (4c exceeding rate [4cER]), which is associated with poor prognosis of patients with oral squamous cell carcinoma. In the multivariate analysis, 3 independent factors were found to significantly influence cause-specific survival. These are, in decreasing order of influence, (1) abnormal DNA content (4cER), (2) clinical stage, and (3) growth type.

CONCLUSION

The presence of cancer cells with abnormal DNA content of the ITF in conjunction with clinical findings (clinical stage and growth type) can give additional useful information when selecting treatment strategies for oral cancer patients.

From pixels to picograms: a beginners' guide to genome quantification by Feulgen image analysis densitometry

The study of genome size variation is important from a number of practical and theoretical perspectives. For example, the long-standing "C-value enigma" relating to the more than 200,000-fold range in eukaryotic genome sizes is best studied from a broad comparative standpoint. Genome size data are also required in detailed analyses of genome structure and evolution. The choice of future genome sequencing projects will be dependent on knowledge regarding the sizes of genomes to be sequenced, and so on. To date, genome size data have been acquired primarily by Feulgen microdensitometry or flow cytometry. Each has several advantages but also important limitations. In this review, we provide a practical guide to the new technique of Feulgen image analysis densitometry. The review is designed for those interested in genome size measurements but not extensively experienced in histochemistry, densitometry, or microscopy. Therefore, relevant historical and technical background information is included. For easy reference, we provide recipes for required reagents, guidelines for cell staining, and a checklist of steps for successful image analysis. We hope that the accuracy, rapidity, and cost-effectiveness of Feulgen image analysis demonstrated here will stimulate further surveys of genome sizes in a variety of taxa.

Topographical analysis of p53 expression and DNA ploidy in early bronchial squamous cell carcinoma and preneoplastic lesions

The significance of p53 mutations and DNA aneuploidy in carcinoma cells has been investigated on the basis of a multi-step development theory of carcinogenesis. It has, however, not been determined whether these alterations can be used as diagnostic markers for the early detection of bronchial squamous cell carcinoma (BSqCC). To address this problem, we topographically investigated p53 alterations and DNA aneuploidy in 24 X-ray-negative, early BSqCC patients with various preneoplastic lesions and in 25 non-carcinoma patients with preneoplastic lesions. Bronchial lesions (n=88) were morphologically classified as hyperplasia (HP, n=5), squamous metaplasia (SM, n=23), low-grade dysplasia (LGD, n=14), high-grade dysplasia (HGD, n=11), intraepithelial carcinoma including 'carcinoma in situ' (CIS) (IEC, n=15), and microinvasive carcinoma (MIC, n=20). Immunohistochemistry for the p53 protein and image cytometry for DNA ploidy detection were performed in serial sections of each lesion. Overexpression of p53 protein was detected in 36, 73, and 65% of the HGD, IEC, and MIC lesions, respectively. Aneuploid DNA profiles were found only in carcinoma lesions, 33% in IEC and 85% in MIC. The topographical analysis revealed two types of early BSqCCs, one with adjacent preneoplastic lesions (sequential type, n=8) and another without such lesions (de novo type, n=16). The p53 protein was frequently overexpressed in both types (sequential type, 79%; de novo type, 62%). In the sequential type, however, the p53 protein was overexpressed in HGD lesions that were directly adjacent to p53-overexpressing carcinoma lesions without exception. The present topographical study suggests that p53 mutations play an important role in the carcinogenesis of BSqCC and that p53-overexpressing HGD lesions in sequential types should be regarded as 'truly' preneoplastic lesions that actually develop into carcinomas. In addition, our study demonstrated that DNA aneuploidy might occur at times after p53 alteration with increasing frequency, as invasive growth begins. Such combination analysis of p53 immunohistochemistry and nuclear DNA ploidy in routine histology may contribute to estimates of malignant potential in preneoplastic and intraepithelial squamous lesions and provide additional information for early detection of BSqCC.