AN EXPONENTIAL-GOMPERTZIAN DESCRIPTION OF LOVO CELL TUMOR-GROWTH FROM INVIVO AND INVITRO DATA

Abstract

The data of nine monolayer cultures, 48 multicellular spheroids, and 19 s.c. xenografts of LoVo cells were fitted, on an individual basis, by exponential and Gompertzian equations, respectively. The mean growth parameters .alpha.o (initial growth rate) and .beta. (retardation factor) of the three experimental systems presented a strong linear correlation .alpha.o = 6.88 .beta. + 0.56, r = 0.9843. This implies that, at the particular tumor size of 155 .mu.m in diameter (mean .+-. SD = 50-310 .mu.m), the tumor growths described by Gompertzian curves (from spheroids as well as from s.c. xenografts) have the same growth rate as monolayer cultures. This occurrence strongly supports an exponential-Gompertzian growth model, where an exponential monolayer-like phase changes to a Gompertzian growth, controlled by environmental conditions, when the tumor size has reached a critical value.