Introduction to Session on Pathology and Epizootiology

Summanr This study u-as aimed at determining whether tumour DNA content measured bv cell image analysis could proVide additional prognostic information when compared to that proVided bv flow cytometry. Sections cut from paraffin blocks of tumours from 101 patients with node negative breast cancer were analysed by both methods and the results related to other prognostic variables and to patient relapse and oserall survisval. DNA ploidy measured by flow cytometry classified 46 tumours as diploid and 55 as aneuploid. whereas bv cell image analysis 30 were diploid and 71 aneuploid (P<0.002). There were 20 tumours With discrepancies betu-een the two methods: 18 of these were tumours with onlv one peak in flouanalysis. but determined to be aneuploid with image analysis. DNA content as measured by both methods was significant for predicting relapse and surviv-al by log-rank test. as were tumour histological grade. c-erbB-2 expression and tumour size. Multivariate analysis showed DNA ploidy measured by flow cytometry to be the only variable of independent significance (P<0.02) for both relapse and overall survival. Compared with cell image analysis. flow cyvtometry demonstrated a significantly higher proportion of diploid tumours. which may be related to differences in the internal standards applied to each method. We suggest that cell image analysis techniques