The cell kinetics of human mammary cancers

: The cellular kinetics of human mammary tumors were studied by in vitro methods. These techniques include single 3HTdR labeling to measure the 3HTdR LI, double labeling with 3HTdR and 14CTdR to measure DNA synthesis time, and an estimation of the growth fraction by the PDP index. Calculations of the potential doubling time and cell cycle time were made from these measurements. The 3HTdR LI of primary malignant tumors was greater than that of benign tumors, but only half that of metastatic lesions. There was considerable heterogeneity in the 3HTdR LI of primary tumors, but the DNA synthesis times were relatively invariant. Estimation of the growth fraction by the PDP index also revealed extensive heterogeneity, but the primary tumors were not different from metastases. There appear to be subsets of tumors with high and low proliferative values that correlate with some clinical parameters, such as age and nodal positivity. This material provides a data base for stratification of patients for future protocols and the use of cell kinetics in treatment programs.