Cytophotometric analysis of corresponding cytological and histological cervical intraepithelial neoplasia grade III specimens

Technologies supporting analytical cytology: clinical, research and drug discovery applications

The tools and techniques developed for analytical cytology have become invaluable in expanding the development of cancer screening programs and biomarker discovery for personalized medicine. Detecting cellular, molecular, and functional changes of diseased tissue as defined by quantitative analytical methodologies has enhanced the field of medical diagnostics and prognostics. The focus of this review is to outline applications and recent technical advances in flow cytometry, laser scanning cytometry, image cytometry, and quantitative image analysis, as they pertain to clinical, research, and drug discovery applications.

Surrogate endpoint biomarkers and their modulation in cervical chemoprevention trials

BACKGROUND

Surrogate endpoint biomarkers (SEBs) are used as intermediate indicators of a reduction in cancer incidence in chemoprevention studies. SEBs should be expressed differentially in normal and high risk tissue; appear at a well defined stage of carcinogenesis; be studied with reasonable sensitivity, specificity, and accuracy; and be modulated in chemoprevention trials. The concept of SEBs may be useful in the trials of many new therapies.

METHODS

The current review includes a comprehensive review of the literature. Many SEBs have been the subject of intense study and include quantitative histopathology and cytology, proliferation markers, regulation markers, differentiation markers, general genomic instability markers, and tissue maintenance markers. Because of the critical biologic and epidemiologic role of the human papillomavirus (HPV) in cervical carcinogenesis, the relation between these markers and HPV should be considered. In addition, biomarkers of HPV infection and its regression should be sought.

RESULTS

Several chemoprevention trials have been published that have included the use of SEBs. The biomarkers that appear most promising in these clinical trials can be measured quantitatively and reproducibly: quantitative histology and cytology, proliferating cell nuclear antigen (PCNA), MIB-1, MPM-2, HPV viral load, epidermal growth factor receptor, polyamines, and ploidy. The markers that have been demonstrated to be modulated in chemoprevention trials in the literature are quantitative histology and cytology, PCNA, MPM-2, HPV viral load, and polyamines.

CONCLUSIONS

The surrogate endpoint biomarkers of most interest in future research should correlate well with HPV infection, be modulated by several therapeutic agents, and have limited variability and ease in measurement.

Chemoprevention trials and surrogate end point biomarkers in the cervix

Cervical cancer is the second most common malignancy in women worldwide and remains a significant health problem for women, especially minority and underserved women. Despite an understanding of the epidemiologic risks, the screening Papanicolaou smear, and morbid and costly treatment, overall survival remains 40%. New strategies, based on the clinical and molecular aspects of cervical carcinogenesis, are desperately needed. Chemoprevention refers to the use of chemical agents to prevent or delay the development of cancer in healthy populations. Chemoprevention studies have several unique features that distinguish them from classic chemotherapeutic trials; these features touch on several disciplines and weave knowledge of the biology of carcinogenesis into the trial design. In the design of chemoprevention trials, four factors are important: high risk cohorts must be identified; suitable medications must be selected; study designs should include Phases I, II, and III; and studies should include the use of surrogate end point biomarkers. Surrogate end point biomarkers are sought because the cancer develops over a long period of time, and studies of chemopreventives would require a huge number of subjects followed for many years. Surrogate end point biomarkers serve as alternative end points for examination of the efficacy of chemopreventives in tissue. High risk cohorts include women with cervical intraepithelial neoplasia (CIN) or squamous intraepithelial lesions (SIL). Nutritional studies have helped define micronutrients of interest (folate, carotenoids, vitamin C, vitamin E). Other medications of interest include retinoids (4-hydroxyphenylretinamide [4-HPR], retinyl acetate gel, topical all-trans-retinoic acid), polyamine synthesis inhibitors (alpha-difluoromethylornithine [DFMO]), and nonsteroidal anti-inflammatory drugs (ibuprofen). Phase I chemoprevention studies of the cervix have tested retinyl acetate gel and all-trans-retinoic acid. Phase II trials of all-trans-retinoic acid, beta-carotene, and folic acid have been and are being carried out, whereas Phase III trials of all-trans-retinoic acid have been completed and have shown significant regression of CIN 2 but not CIN 3. Phase I studies of DFMO and Phase II studies of DFMO and 4-HPR are underway. Surrogate end point biomarkers under study include (1) quantitative cytology and histopathology; (2) human papillomavirus type testing; (3) biologic measures of proliferation, regulation, differentiation, and genomic instability; and 4) fluorescence spectroscopic emission. Clinical trials with biologic end points will contribute to our understanding of the neoplastic process and hence aid us in developing new preventive and therapeutic strategies.

DNA quantification is technically feasible and of value in cervical smear samples: possible applications for determination of progression in low grade dyskaryosis

This study evaluates the feasibility of DNA analysis of cervical intraepithelial neoplasia III (CIN III) lesions on cervical smear and formalin-fixed paraffin-embedded tissue (FFPET) blocks with a view to extending this type of analysis to milder grades of dyskaryosis. DNA ploidy was determined by image analysis using a CAS 200 Image Analyser. Seventeen patients with a diagnosis of CIN III were studied. Results show that all smear and tissue samples were non-diploid with nine aneuploid and eight tetraploid lesions. In 6/7 patients whose smears and corresponding biopsies were examined there was complete agreement as to the DNA profile. We conclude that DNA quantification is technically feasible in archival, routinely prepared cervical smears. This technique should now be applied to CINI and CINII cervical smears to determine if it is of value in identifying those lesions that will progress to CIN III. This study is particularly timely with the possibility in the near future of estimation of ploidy by image analysis using instruments such as the Highly Optimized Microscope Environment (HOME) system.

A thionin stain for visualizing bone cells, mineralizing fronts and cement lines in undecalcified bone sections

A staining method is described using thionin, for undecalcified deacrylated bone sections. RNA is stained purplish violet, allowing still active osteoblasts to be distinguished from lining cells. Staining intensity of mineralized bone is related to the degree of mineralization. Mineralizing fronts and cement lines are visualized clearly. Lamellae show an alternate pattern. Histomorphometric parameters such as osteon thickness and interstitial bone thickness can be measured without using polarized light. The mineralizing front can be assessed and expressed as a percentage of the osteoblast-covered interface between osteoid and mineralized bone. The stain is also useful for qualitative assessment of metabolic bone disease. Thionin stained sections can be kept for at least one year when stored in the dark at 7 C.

Study of numerical aberrations of chromosome 1 by fluorescent in situ hybridization and DNA content by densitometric analysis on (pre)-malignant cervical lesions

In an attempt to determine whether the fluorescent in situ hybridization (FISH) can be used as a rapid approach for the identification of aneuploidy in premalignant cervical smears, a centromeric probe for chromosome 1 was used. The results from the FISH experiments were compared with measurements of the overall DNA content obtained by means of an image analysis system. With progression to neoplasia, a decrease of the frequency of cells with two spots was observed, due to an increasing polysomy of chromosome 1. As far as the DNA content was concerned, an increasing DNA index and 5C-exceeding ratio (fraction of cells with a DNA content higher than 5C) was observed. Classification of the FISH results by a linear discriminant analysis revealed that 67.6% of the cases were classified in agreement with the CIN classification. These data suggest that chromosome 1 may be considered as a marker chromosome for pre-malignant cervical lesions and that the DNA content measurements are complementary to the FISH results.

Detection of premalignant stages in cervical smears with a biotinylated probe for chromosome 1

Fluorescence in situ hybridization with (peri-)centromeric probes is an easy method to detect numerical aberrations in nonmitotic and mitotic cells. In this study, cervical smears of premalignant and malignant stages (26 controls, 15 CIN I, 12 CIN II, and 15 CIN III cervical smears) were analyzed for the presence of numerical aberrations of chromosome 1 with a centromeric DNA probe (1q12). With more severe stages a decrease of disomy was observed, merely due to a gain of extra copies of chromosome 1; in some cases, however, monosomy was detected. The frequencies of disomy for chromosome 1 ranged from 65.3% to 95.0% in the controls, from 71.3% to 94.3% in CIN I, from 59.2% to 91.5% in CIN II, and from 23% to 96.2% in CIN III. Polysomy ranged from 0% to 5.7% in the controls, from 0% to 14.4% in CIN I, from 0.9% to 30.8% in CIN II, and from 0.8% to 69.6% in CIN III. Monosomy ranged from 2.6% to 34.1% in the controls, from 0% to 17.5% in CIN I, from 3.6% to 27.5% in CIN II, and from 0.9% to 31.4% in CIN III. The results show that screening for aneuploidy of chromosome 1 allows a good discrimination between control samples and dysplasia. These data suggest that chromosome 1 may be a marker chromosome. They are in accordance with previous cytodensitometric analyses, where already in the preneoplastic stages an increased DNA content (polyploidization with subsequent aneuploidization) is observed.

Quantitative DNA measurement by flow cytometry and image analysis of human nonseminomatous germ cell testicular tumors

Current clinical staging, which includes the use of serum tumor markers and imaging techniques, fails to identify the 30-40% of clinical stage I (CS I) nonseminomatous germ cell testicular tumor (NSGCT) patients who have occult metastatic disease. Therefore, there is a real clinical need to evaluate new biological parameters of the primary tumor that might be useful as predictors of occult metastatic disease. This study was undertaken to compare quantitative DNA measurements by flow cytometry and image analysis in CS I NSGCT, and to analyze the relevance of these parameters for predicting occult lymph node involvement. Different blocks of formalin-fixed, paraffin-embedded NSGCTs of 62 CS I patients who underwent retroperitoneal lymph node dissection between 1985 and 1989 were prepared according to the Hedley technique, and analyzed by quantitative cytometry. Thirty-six (58.1%) patients had histologically proven lymph node involvement (pathological stage II), whereas 26 (41.9%) patients (pathological stage I) had neither lymph node metastases according to retroperitoneal lymph node dissection (RPLND) specimens nor tumor recurrence during follow-up. Concordant results were found in 76.5% of the samples by both cytometric techniques. For flow cytometry, the percentages of aneuploid cells in the S- and the G2M + S-phase were the most robust predictive parameters for lymph node involvement, whereas for image analysis the 5c exceeding rate (5cER) had the most predictive significance. Based on the experience obtained in this study, both cytometric techniques provide additional information on tumor aggressiveness that might be useful in therapeutic selection of early stage NSGCT patients for either RPLND or surveillance only.