Comparison of in vivo and in vitro activity of estrogen-linked nitrosoureas in methylnitrosourea-induced rat mammary carcinoma.

The anticancer activity of estradiol-linked 2-chloroethylnitrosoureas in methylnitrosourea-induced rat mammary carcinoma was investigated using the short-term assay and the bilayer soft agar system after in vitro exposure as well as the monolayer methylcellulose assay following in vivo treatment. The aim was to evaluate to what extent previous in vivo findings are paralleled by the results of two in vitro test systems and the monolayer culture technique ex vivo. From the test systems investigated and under the conditions used, the results of the short-term test and the monolayer methylcellulose assay did not show a correlation with previous in vivo findings. Only the results of the bilayer clonogenic assay paralleled therapeutic parameters in vivo, although the degree of activity obtained in vivo was not reflected in vitro.