6th ESACP Congress, Heidelberg, April 7-11, 1999

A038
IMPROVED OBJECTIVITY OF GRAD IN Ta,1 URINARY BLADDER TUMORS BY MORPHOMERIC PROLOFERATION AND DIFFERENTIATION ASSOCIATED FEATURES AND KI-67 IMMUNOQUANTITATION
Bol MGW, Schuurmans LS, Baak JPA

Departments of Pathology, Academic Hospital Free University, Amsterdam, Medical Center Alkmaar, Netherlands

Background: The grade of Ta,1 urinary bladder tumors has therapeutic impact, but intra- and interobserver reproducibility is poor. Previous studies have shown that morphometric analysis of mean nuclear area of value for objective grading. Objective: To analyse with single- and multivariate analysis whether mitotic activity index (MAI), nuclear area features and Ki-67 immunoquantitation, have additional discriminative value to each other in different grades of Ta,1 bladder tumors. Material & Methods: 150 consecutive Ta,1 urinary bladder tumors have been analysed. Duplicate blind assessment of grade was performed by three independent observations in standard HE-paraffin sections, which were also used for morphometric analysis. The QPRODIT 6.1 system (Leica, Cambridge, UK) was used for morphometric analysis and immunoquantitation of Ki-67. Single and multivariate analysis was applied to discriminate the different grades. Results: In the learning set (n=17 grade 1, 30 grade 2, 28 grade 3) the best discriminating features were MAI and Ki-67, and to a lesser degree the mean of the area of the ten largest nuclei. With multivariate analysis, all three features were included. The best discriminating features between grade 1 and 2 were MNA-10 and MAI, and between grade 2 and 3 the MAI and Ki-67. With these features, 93.6% of the original grade 1 and 2 cases were correctly classified (3 of the grade 2 cases were classified as grade 1). Of the grade 2 and 3 cases, 96.6 % was correctly classified (2 grade 3 cases were classified as grade 2). In the test set, the classification results were similar (89.4% of the grade 1 versus 2 and 94.8% of the grade 2 versus 3 were correctly classified). Conclusions: 1. Combination of MAI, Ki-67 and MNA-10 gives much better discrimination between grade 1, 2 and 3 Ta,1 urinary bladder tumors than MNA-10 alone. 2. The similarity of the classification results of the test set and the learning set encourage us to apply the classification model in a prospective analysis.
Literature:
Blomjous et al, 1989, Anal. Quant. Cytol. Histol. 11: 426-437