Prediction of long-term survival by flow cytometric analysis of cellular DNA content in patients with advanced ovarian cancer.

The prognostic value of cellular DNA content in ovarian cancer (malignant common epithelial tumors) was investigated by flow cytometric analysis of paraffin-embedded tumor blocks from 128 previously untreated patients with International Federation of Gynecology and Obstetrics (FIGO) stage III and IV ovarian cancer entered in a prospective clinical trial of combination v sequential therapy with chlorambucil and cisplatin. Seventy-three percent of tumors were aneuploid and 27% were diploid. Multivariate analysis using a Cox model showed that cellular DNA content (P less than .001) and FIGO stage (P less than .02) were the only significant independent prognostic variables. The median survival was 13 months for patients with aneuploid tumors and 60 months for patients with diploid tumors (P less than .0001). Further analysis indicated that the good prognosis associated with diploid tumors was limited to patients with stage III disease, all patients with stage IV (spread beyond the peritoneal cavity or liver metastases) disease having a poor prognosis irrespective of ploidy. On pathological review, nine borderline ovarian tumors (of low malignant potential) were identified, and seven of these were diploid. These tumors have an unusually favorable prognosis, despite apparent dissemination within the peritoneal cavity, a paradox which is often difficult to explain using conventional histological criteria. Although the vast majority of tumors in this study (93%) were classified as invasive epithelial ovarian cancers, it is possible that some of the patients with stage III diploid tumors may have had malignancies that were predominantly of low malignant potential, thus accounting in part for the prognostic significance of DNA content. By incorporating flow cytometric DNA analysis with careful histopathological assessment, it may be possible to better identify patients with an inherently good prognosis. This assumes particular importance, as the relatively favorable prognosis of patients with stage III diploid ovarian tumors appears to be independent of the type of treatment.