Calculation of percentage of hormone independent transplantable cells in experimental mammary tumors.

Some cancer types (e.g. breast cancers) are known to consist of mixed populations of cells which respond to hormones, and cells that do not. A theoretical model is proposed to investigate the proportion of these different cell types in experimental tumors. The model exploits the fact that when grafts are treated with hormones, both cell types form an outgrowth, whereas in the absence of hormones only the autonomous cell types can grow. Method 1 consists of serially transplanting the tumor to be investigated in castrated mice that are not treated with hormones, and comparing the growth rates of two consecutive transplant generations. Method 2 involves comparing the growth of the tumor in hormone treated and untreated castrated mice. The merits and limitation of each of these two methods are discussed.