THE GROWTH CURVE OF THE FIRST PASSAGE XENOGRAFTS OF HUMAN TUMORS IN NUDE-MICE PREDICTS THEIR TRANSPLANTATION BEHAVIOR

The patterns of macroscopic growth of 20 first generation human tumor xenografts (16 renal cell carcinomas and 4 squamous cell carcinomas of the head and neck region) were studied with the recursion formula of the Gompertz function. This method enables the characterization of eac h tumor growth pattern by two parameters: (i) parameter a, which corre lates with the starting growth rate of the tumor and (ii) parameter b, which is a measure of the intensity of growth deceleration as a funct ion of tumor growth. A statistically significant prediction of the est ablishment of a xeno-transplantation line after serial subpassaging (i n 9/20 tumors) according to the characteristics of first passage growt h curves (p<0.01) is reported. Especially parameter b, the value of th e growth deceleration, highly correlates with serial growth: tumors sh owing less growth deceleration (higher b-values) during first passage more frequently develop into transplantation lines. On the contrary li ne development could not be predicted on the basis of the a-values of the first passage growth curves alone (p=0.137). This observation adds to the accumulating evidence, that the process of tumor growth decele ration is a pivotal parameter of tumor biology. Moreover, the present evaluation substantially reduces the time needed to assay serial growt h of tumor xenografts for prognostic purposes making this assay potent ially more attractive for clinical use.