Comparison of flow cytometric DNA content analysis in fresh and paraffin-embedded ovarian neoplasms: a prospective study

DNA ploidy analysis was performed on both fresh and paraffin-embedded preparations from each of 54 malignant ovarian neoplasms. Aneuploidy was detected in both the fresh and the paraffin-embedded tissue in 19 out of 54 (35%) malignant cases. In addition, aneuploidy was detected exclusively in fresh tissue in seven of the malignant cases, and exclusively in paraffin-embedded tissue in one of the malignant cases, yielding a total of 27 out of 54 (50%) aneuploid cases. The correlation coefficient (r-value) for fresh and paraffin-embedded tissue ploidy analysis in the malignant specimens was 0.91. Although the frequency of recurrence was higher and overall survival lower in the malignant aneuploid specimens of both types, the combined analysis of DNA and survival rates indicated superior prognostic significance of fresh tissue. Of the seven patients in whose specimens aneuploidy was detected exclusively in fresh tissue, all died of recurrent disease during the follow-up period. Our finding indicates that data generated by flow cytometry analysis of formalin-fixed tissue should be interpreted with caution before the data can be used to draw clinical inferences.