Prognostic significance of DNA index, multiploidy, and S-phase fraction in ovarian cancer.

Paraffin-embedded tumor samples from 157 ovarian cancer patients were analyzed by DNA flow cytometry. Tumor ploidy had prognostic significance in both early and advanced ovarian cancer. After adjusting for stage, residual tumor mass, histopathologic type, treatment, and age of patient in a Cox regression analysis, the relative risk of death was two-fold higher in single DNA-aneuploid and sixfold higher in DNA-multiploid tumors as compared to DNA-diploid tumors (P less than 0.0001). A tetraploid DNA index was associated with a relatively low risk ratio, whereas hypertetraploid tumors were highly malignant. S-phase fraction (SPF) had prognostic value especially in DNA-diploid tumors. The simultaneous evaluation of DNA index, the number of aneuploid cell clones, and SPF gave more prognostic information than the determination of tumor ploidy alone. On the basis of these parameters we have developed a classification of tumor DNA histograms for better prognostic assessment of ovarian cancer.