Cellular DNA content--a stable feature in epithelial ovarian cancer.

Detailed flow cytometric analysis of cellular DNA content was performed on neoplastic tissue from 33 patients with malignant common epithelial ovarian tumours in order to investigate the intratumoral stability of ploidy and proliferative fraction. There was a remarkable stability, both spatial and temporal, in the DNA pattern for any particular tumour. Of 24 tumours that were analysed in multiple areas tumour ploidy was found to be a stable marker in all but 3 cases where regional variations were evident. In 9 patients serial analyses were performed on tumour obtained either at initial diagnosis (6 patients) or second look laparotomy (3 patients) and then some time later (7-17 months) at relapse or death and in all cases the tumour ploidy remained unchanged. In addition, 10 ovarian carcinomas established in nude mice have maintained a DNA content during serial passage similar to that of the original implanted tumour. In contrast in 50% of tumours that were evaluable for S-phase analysis we demonstrated a considerable intratumoral variability in the S-phase fraction. We conclude that cellular DNA content is a stable feature of ovarian carcinoma while S-phase fraction is commonly subject to intratumoral variation.