Concordance of DNA ploidy pattern as measured by flow cytometry in primary, metastatic, and persistent ovarian carcinoma

In an attempt to evaluate the stability of DNA content in ovarian carcinoma, 66 tumor specimens from 25 patients with stage III disease were analyzed by flow cytometry. For all patients, both primary tumor and omental metastasis were available, and for 16 patients the persistent tumor found at second-look operation was also available. The concordance of the tumor DNA content in the primary tumor and in the corresponding omental metastasis was 72%; the concordance in persistent tumor at second-look operation was 63%. When diploid and aneuploid tumors with very low DNA index were considered together, the concordance of the DNA content in primary and metastatic tumors reached 84%. According to our data, if DNA ploidy is used to differentiate patients with a favorable prognosis (DNA diploid and DNA aneuploid with low DNA index) from those with an unfavorable prognosis (DNA aneuploid with high DNA index), a 16% risk of misclassification appears unacceptable in prospective studies. Hence, the assessment of two specimens (preferably the primary lesion and a metastatic site) to determine the most abnormal DNA ploidy result would reduce the risk of underclassification of tumor.