Cell kinetics in vivo of human breast cancer.

Rates of cell proliferation within tumours may provide prognostic information and help in the rational administration of chemotherapy and radiotherapy. In vivo labelling with 5-bromo-2'-deoxyuridine (BrdU) was used in 89 women with breast cancer to determine the labelling index for BrdU (BLI), the length of S phase (TS) and the potential doubling time of the tumour (Tpot). Kinetic data were obtained in 84 patients. The median BLI was 3.2 per cent, TS 12 h, and Tpot 12.5 days. There was no systematic difference in the labelling index determined by flow cytometry and by manual counting on sections. Labelling indices were significantly higher in aneuploid tumours, and in tumours not expressing oestrogen receptors, but were not correlated with tumour size, nodal status, or expression of c-erbB2. In vivo measurement of tumour cell kinetics can be made rapidly and reliably in the majority of human breast cancers, and may have a role to play in planning therapy.