The proliferative index (PI) of human breast cancer as obtained by flow cytometry.

As known from previous reports, the DNA synthesis fraction of mammary carcinoma cells is correlated with the course of the disease and response to adjuvant therapy. Quantitative parameters of the proliferative activity can be determined by the classic 3HTdR-labelling technique as well as by the more rapid flow cytometric (FCM) DNA analysis. The values of DNA-cytometric S-phase fractions in breast cancers reported up to now were consistently higher than those obtained by the 3HTdR labelling index (LI). This discrepancy was surmounted in the present study by corrections for systemic errors of the method. The fractions of cells in stages of the cell cycle as well as the DNA indices (DI) in 155 cases of primary resectable breast cancers were analyzed by DNA flow cytometry. The patients were aged between 24 and 88 years. As indicated by a bimodal age distribution with a decrease at age 60, the patient population was a representative of the generally known breast cancer incidence. 54% of the patients had aneuploid tumor cells with preferences of DNA indices 1.6 and 2.0. In the remaining 46%, no cell populations with deviating DNA content could be detected, in part possibly due to very small differences beyond the limits of detection. No correlations were found between age, menopausal status, histologic type of tumors, tumor size, fractions in stages of the cell cycle and proliferative index (PI = S + G2 + M in %), except a significant correlation between the S-phase fractions and the (G2 + M)-phase fractions in a ratio of approximately 1.(ABSTRACT TRUNCATED AT 250 WORDS)