Body Size and Lung-Tumor Susceptibility in Outbred Mice

During a series of experiments on the genetic control of susceptibility to induced lung tumors involving normal mice from two outbred stocks, information was collected on the weights at various ages and on the tail length of each mouse. This paper gives the results of statistical analysis of these data, thus providing information on the relationship of weight and growth with induced lung-tumor susceptibility in a large number of normal outbred mice. The outbred stocks JC and LX were chosen because of their difference in size. The larger LX mice were considerably more susceptible to urethan-induced lung tumors than the JC mice. However, the simple hypothesis that the LX mice were more susceptible because they were bigger was not borne out. Within a stock, the only statistically significant relationship between weight and susceptibility was at 3 weeks of age and this correlation was negative, i.e., the smaller the mouse at this age the greater its susceptibility. Possible explanations of this finding are discussed in relation to the work of other authors.