Studies of the growth, population kinetics, and host lethality of CD8F mammary adenocarcinoma.

First-generation transplants of spontaneous mammary adenocarcinomas in CDSF mice have been included in the tumor panel used for the screening of potential anticancer chemotherapeutic agents. Studies were undertaken to evaluate the growth and kinetic characteristics to provide a better understanding of the basic biology of the tumor system. The spontaneous mammary adenocarcinomas are highly variable in growth rate, and this characteristic is seen to a lesser extent in the transplanted tumors. The doubling time of the transplants is usually, but not always shorter than the doubling time of the donor tumor at a similar mass. The median length of the cell cycle obtained from pooled data from first-generation transplants of four donor tumors is 15.6 hours with a median S phase of 9.5 hours. The thymidine indices (TI) ranged from a mean of 0.28 at 100 mg to a mean of 0.20 when tumors ranged from 3 to 6 g. The mean TI of tumors of all sizes is 0.27. The cell cycle parameters and TIs appear to be characteristic of the tumor system and apparently do not vary with characteristics of the donor tumor. These studies also indicate that these kinetic parameters are not responsible for the variation in volume doubling time of the transplanted tumors.