Cytophotometric characterization of the WHO grades of transitional cell neoplasms

[Karyometry of BBN-induced precancerosis of the urothelium : An experimental analysis]

BACKGROUND

The morphology of experimental precancerous lesions of the urinary bladder has been interpreted quite differently by various authors.

OBJECTIVES

The aim of this investigation was to quantify these lesions by karyometry and, thus, to gain a more reliable understanding of the process.

MATERIALS AND METHODS

A total of 60 Wistar rats were fed with N‑butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at a concentration of 0.05 % in their drinking water to induce preneoplastic changes of the urothelium. After the second week of BBN exposition, 6 animals were killed every 2 weeks up to week 20. Smears of the scraped off urothelium of 3 urinary bladders of each group were analyzed cytologically and karyometrically.

RESULTS

BBN exposition led to statistically significant changes of the karyometric values using the χ² test to differentiate the control animals from the ones that had ingested BBN and the 2‑week groups from each other. These changes consisted mainly in significant deviations of the size of the nuclear area within the different groups.

CONCLUSION

Morphological and karyometrical analysis showed that biologically relevant stages in the development of chemically induced urothelial precancerous lesions could be realized much earlier than had been assumed in recent publications. Karyometric analysis offered a valid basis to describe the early morphologic alterations of carcinogenesis.

Cell proliferation indices, morphometry and DNA flow cytometry provide objective criteria for distinguishing low and high grade bladder carcinomas

Argyrophilic nucleolar organizer region (Ag-NOR) analysis, proliferating cell nuclear antigen (PC-NA/PC10) and MIB-1 immunohistochemistry, nuclear morphometry and DNA flow cytometry have been performed on formalin-fixed, paraffin-embedded biopsies from 50 patients with transitional cell carcinoma of the urinary bladder. The mean AgNOR count was 6.01 for the 17 grade 1 (G1), 7.59 for the 21 G2 and 13.33 for the 12 G3 carcinomas (p < 0.001). The mean PCNA score was 15.03% for G1, 24.04% for G2 and 40.01% for G3 cases (p < 0.001). The mean MIB-1 score was 11.31% for G1, 17.09% for G2 and 34.47% for G3 carcinomas (p < 0.001). The mean nuclear area was 35.53 microns2 for G1, 38.65 microns2 for G2 and 83.62 microns2 for G3 cases (p < 0.001). Aneuploidy rates were significantly higher (91.7%) in G3 than in G2 (42.9%, p < 0.01) or G1 cases (47.1%, p < 0.05) but not different for G1 versus G2 cases (p = 0.94). While many overlaps of values were seen between G1 and G2 tumours, no overlaps were found between G3 and G1/G2 tumours. Significant differences of values were also found between pTa and invasive tumours (p < 0.0001 for AgNOR count and PCNA score; p < 0.001 for MIB-1 score and mean nuclear area; p < 0.01 for DNA ploidy); however many overlaps were seen. Our findings indicate that the quantitative parameters obtained with different methods are associated with histological grade of bladder urotheliomas and may improve the grading reproducibility. In addition, the absence of overlaps between G3 and G2/G1 carcinomas supports the tendency to classify bladder urotheliomas in only two categories of malignancy.

Quantitative histopathology in the prognostic evaluation of patients with transitional cell carcinoma of the urinary bladder

BACKGROUND

Morphologic grading of malignancy is considered to be of prognostic value in patients with transitional cell carcinomas of the urinary bladder (TCC). This qualitative approach is, however, associated with low reproducibility. Grading of malignancy can be carried out on a reproducible, quantitative scale.

METHODS

A retrospective, prognostic study of 110 patients treated for TCC in clinical Stages Ta-T4 (median follow-up time, 6 years) was performed, evaluating various grading techniques. Unbiased estimates of the volume-weighted mean nuclear volume (nuclear vV), nuclear volume fraction, estimates of nuclear mean profile area (aH(nuc)), nuclear profile density index (NI), and mitotic profile density index (MI) were obtained by stereologic and morphometric techniques.

RESULTS

The T-stage and morphologic grade of malignancy were closely cross-correlated (+0.63 < Kendall tau < +0.71, 2P < 6.7 x 10(-16)). The estimation of nuclear vV was highly efficient, with more than 85% of the associated variation attributable to differences between tumors. A positive significant correlation between estimates of nuclear vV and aH(nuc) was detected (r = +0.79), whereas an inverse correlation was documented between nuclear vV and NI (r = -0.63). Estimates of nuclear volume fraction showed no correlation with nuclear vV. Comparisons between categorical and quantitative data revealed the following: a decrease in averaged estimates of NI for tumors in advanced T-stage and malignancy grade (2P < 0.0008); and nuclear vV and aH(nuc) increased on average, in tumors of high T-stage and malignancy grade. Estimates of MI were also positively correlated with the T-stage and the malignancy grade (+0.42 < Kendall tau < +0.49). Single-factor analyses showed prognostic effect of T-stage, grade of malignancy, and, apart from nuclear volume fraction, all quantitative histopathologic variables with regard to overall survival (2P < 0.03). None of the morphometric and stereologic parameters were of prognostic values with regard to recurrence-free survival (2P > 0.26). Multiple hazards regression analysis (Cox models) revealed that clinical stage of disease was the sole independent prognostic variable. Only estimates of nuclear vV added significant independent prognostic prediction with regard to recurrence-free survival in the 48 patients with Ta tumors (2P = 0.03).

CONCLUSIONS

The results suggested that estimates of nuclear vV are prognostically superior to morphologic grading of malignancy in noninvasive TCC, whereas both morphologically and quantitatively based malignancy grading are without prognostic value in invasive TCC.

The prognostic significance of selective nuclear morphometry in urinary bladder carcinoma

Transurethral resected tumor specimens of 61 patients with a primary and untreated bladder carcinoma were studied by selective nuclear morphometry, a method recently described by us. A significant enlargement of the mean nuclear area was found with the advance of tumor grade and stage (Wilcoxon, P less than .0001 and P less than .0001). The heterogeneity of the grade 2 patient group and the additional value of morphometry were demonstrated by observing the 5-year survival rates. Patients with grade 2 carcinoma could be separated into one subgroup with small nuclei (mean nuclear area less than or equal to 95 microns2) having a favorable outcome (5-year survival rate: 100%), and into another subgroup with large nuclei (mean nuclear area greater than 95 microns2) showing a worse prognosis (5-year survival rate: 63.2%) (Mantel-Cox, P = .01). The outcome of these subgroups was not significantly different from that of the grade 1 (5-year survival rate: 93.8%) and grade 3 (5-year survival rate: 50%) patients, respectively (Mantel-Cox, P = .45 and P = .57). The value of selective nuclear morphometry, in addition to tumor staging, was indicated by the association of nuclear enlargement (mean nuclear area greater than 95 microns2) with progressive recurrence (five of 15 patients; 33%) among the patients with conservatively treated superficial carcinoma (stages Ta and Tl). The findings demonstrate the supplementary value of selective nuclear morphometry to tumor grading and staging, especially in the heterogeneous group of grade 2 carcinomas and the group of superficial tumors (stages Ta and Tl).

Comparison of quantitative and classic prognosticators in urinary bladder carcinoma. A multivariate analysis of DNA flow cytometric, nuclear morphometric and clinicopathological features

The prognostic value of nuclear morphometry and DNA flow cytometry of paraffin embedded material of 58 patients with primary and untreated transitional cell carcinoma of the bladder was compared with that of histological grade (WHO-system), tumour stage (TNM-classification), tumour size, multiplicity and ulceration. Small nuclear size (mean nuclear area less than or equal to 95 microns2) (n = 25) and DNA diploidy (n = 28) indicated a favourable outcome (5-year survival 95.8% and 92.2%); large nuclei (mean nuclear area greater than 95 microns2) (n = 33) and DNA aneuploidy (n = 30) indicated a worse prognosis (5-year survival 61.4% and 62.5%) (Mantel-Cox; p = 0.002 and p = 0.007). The quantitative techniques had the advantage over subjective histological grading that distinguishment of an intermediate patient group (WHO-system: grade 2; n = 32) with heterogeneous outcome (5-year survival 78%) was avoided. Multivariate analysis showed tumour stage as the most important prognosticator of survival. Neither the quantitative techniques, nor the other classic features added significantly to the prediction. The additional value of the quantitative techniques was however shown in superficial carcinoma (TNM-classification: stage Ta and T1; n = 37); large nuclei (mean nuclear area greater than 95 microns2) (n = 15) and aneuploid DNA peaks (n = 13) were associated with progressive recurrent tumour (n = 7) (Mantel-Cox: p = 0.03 and p = 0.0004). The quantitative methods thus indicate which patients are at risk for progression and may enable more appropriate treatment at an earlier stage of disease.

A rapid system for static cytofluorometry enabling the simultaneous determination of nuclear size and DNA content

A measuring technique enabling the simultaneous determination of nuclear size and DNA content by single cell cytofluorometry is described. The system is based on a Leitz MPV cytophotometer, a Zeiss scanning stage and a microcomputer system. Cells to be measured are not positioned in the ordinary way, but are passed through the excitation light beam. In this way rapid measurements are achieved. Further, an estimate of the object diameter is calculated from the pulse shape obtained as the fluorescence is recorded continuously by using a circular measuring aperture, congruent with the excitation light field. Repeated measurements of nuclei stained with Hoechst 33258 showed a high reproducibility for DNA content with a coefficient of variation (CV) below 1% and an acceptable precision for nuclear area with a mean CV of 7%. Nuclear area estimated by the method was well correlated to area determined from photographs (r = 0.986). Disintegrated samples from eight patients with breast cancer were analyzed and compared to Feulgen-stained samples analyzed by scanning cytophotometry. Scatter diagrams illustrating DNA content and nuclear size showed essentially the same distribution with the two methods. We conclude that the system may be a rapid alternative when fluorescence together with object size are quantified in slide preparations.

Correlation between in vitro autoradiographic results and histological WHO grades in human urothelial bladder tumours

253 biopsy specimens of 106 urinary bladder tumours have been examined by means of in vitro autoradiography and the results compared with the WHO grading. An increase of the average labelling index occurred parallel to increasing WHO grades. However, great inter-tumorous differences in proliferation behaviour existed particularly in papillary G2 and G3 urothelium carcinomas. Possible causes of this heterogeneity are discussed. In vitro autoradiography is a suitable method for the objective characterization of the malignancy potential of urinary bladder tumours.

Clinical and biological significance of aneuploidy in human tumours

Aneuploidy is a well recognised feature of human tumours, but the investigation of its biological and clinical significance has been hampered by technological constraints. Quantitative DNA analysis reflects the total chromosomal content of tumour cells and can now be determined rapidly and reliably using flow cytometry; this has resulted in renewed interest in its potential clinical applications. This article reviews the accumulating evidence that tumour ploidy reflects the biological behaviour of a large number of tumour types and that diploid tumours in particular have a relatively good prognosis. The measurement of tumour ploidy is likely to become a valuable adjunct to the clinical and histopathological assessment of cancers.

Karyometric investigations on urinary bladder carcinoma, correlated to histopathological grading

The aim of this study is to provide karyometric data which may be of value in the grading of urinary bladder tumours. For this purpose 27 biopsies were studied: four from normal bladder mucosae, eleven from grade I tumours, six from grade II tumours and another six from grade III tumours, according to a I-IV scale. After standardized fixation and plastic embedding, semithin sections were used for light microscopic stereology. Mean profile areas and mean volume densities of the nuclei tended to be higher in the more malignant cases. The nuclear volume densities were significantly higher in grade II than in grade I. The most important finding relates to the large nuclear profiles (greater than 90 microns 2), which were found almost exclusively in grade III tumours. Simple measurements of nuclear size can thus provide objective data to aid in the diagnostic procedure.

Histopathological subgrouping of WHO II urothelial neoplasms by cytophotometric measurements of nuclear atypia

The grade of nuclear atypia was objectively assessed in 21 cases of non-invasive WHO II transitional cell bladder neoplasm. Measurements were performed by stage scanning absorbance cytophotometry, registering nuclear optical density, nuclear area, and the variability of these two factors, in 5 microns thick Feulgen-stained paraffin sections. The material was subgrouped into a 2- and a 2+ group according to the degree of histopathological atypia. Cytophotometrically determined atypia showed close correlation to the subjectively judged atypia, and there was no overlap between 2- and 2+. A difference in tumour ploidy level between different WHO II tumours is the most likely explanation of the grouping recorded.

HISTOSCAN: computer program for cytophotometry in tissue sections and its application in the evaluation of nuclear atypia

The grading of nuclear atypia has a great and well recognized value when predicting the malignancy of neoplastic processes. Although the basic criteria for the grading are generally agreed upon, in the individual case, the final judgement is to some extent still a matter of subjectivity, which naturally impairs reproducibility. The present paper describes a method for quantification of variability of nuclear size and Feulgen-stainability. By plotting the mean optical density against the area value in a scatter-diagram, a cluster is obtained, the size of which reflects the degree of nuclear atypia. The measurements are performed in tissue sections using stage scanning cytophotometry. A computer program--HISTOSCAN--has been developed which enables measurements in highly cellular tissues. The system is also insensitive to the influence of light scattering, a factor of importance when measuring in tissue sections. The performance of the program is tested in both imprints and tissue sections.