Ploidy as a prognostic factor in ovarian cancer.

The cellular DNA content of 50 ovarian common epithelial carcinomas was determined by flow cytometry, and tumours were classified as being either diploid or aneuploid. A significant association between tumour stage and ploidy was demonstrated, with all diploid tumours being of an early stage (p less than 0.001). Forty percent of early-stage tumours (FIGO stages I and II) and all late-stage tumours (FIGO stages III and IV) were aneuploid. This heterogeneity with respect to DNA content among tumours of a similar stage may allow the identification of neoplasms with a different natural history. The proportion of S-phase cells determined by flow cytometry is a measure of cellular proliferation and may also be of prognostic significance. Diploid tumours had a median S phase of 9.8% (2.4-14.1%), while aneuploid tumours had a significantly higher S phase of 19.6% (7-24.7%; p less than 0.05). In this study there was no relationship between histological grading of invasive carcinomas and ploidy, but in view of the relatively small numbers and limited follow-up, it was not possible to perform a multivariate analysis of all known prognostic factors in ovarian cancer. Our results suggest that ploidy reflects tumour behaviour, but prolonged follow-up and increased patient accrual is necessary to assess whether the flow cytometric analysis of DNA content will provide clinically important information in ovarian cancer.