Comparative investigations on the effect of the phase-specific drug vincristine (VCR) on the proliferation kinetics of a solid experimental tumor.

The aim of the present investigation was to compare the effects of repeated and single applications of vincristine (VCR) to a solid tumor in mice during the phase of tumor growth retardation 14 days after transplantation. Furthermore an attempt was made to induce synchronized tumor cell proliferation. Retardation of volume growth was found to be very much more pronounced after repeated application of VCR than after a single dose of this cytostatic drug. The intensity of the effect decreased within the tumor itself from the periphery to the centre. A synchronization of tumor cell proliferation by flow out from the mitotic block or by a high simultaneous recruitment of previously noncycling tumor cells into the cell cycle could not be demonstrated.