Are Cell Kinetic Data Relevant for the Design of Tumour Chemotherapy Schedules?*

The data on the importance of the application of information on cell kinetics for the success of tumour chemotherapy are critically reviewed. It is concluded that the data on cell sensitivity to drugs as affected by cell kinetic variables are as yet insufficient to permit the prediction of optimal dosage schedules for tumour therapy. More information is needed on differential responses and differential kinetic features of normal and malignant tissues. Optimistic views of cell kinetics as an easy answer to the problems of drug dosage schedule design are unjustified, but so is the disenchantment with cell kinetics as a fruitful approach. Much further work, especially on the drug sensitivity of cellular compartments in slow growing tumours, is needed before a complete evaluation of this tool is possible.