A study on hormone dependency of breast cancer.

Sex hormone dependency of breast cancer was studied in vitro by examining 3H-thymidine uptake into DNA of breast cancer cells. DMBA induced breast cancer of rats, Shionogi carcinoma 115 and Shionogi carcinoma 42 of mice were studied preliminarily. These 3 kinds of rodent breast cancer showed the same sensitivity to both sex hormones in vitro as has been shown biologically. Subsequently, this sensitivity test was applied to human breast cancer. The results were not so simple as in rodent breast cancer, but rather complicated. Human breast cancers were classified into estrogen dependent group, estrogen independent group and estrogen suppressive group, according to their sensitivity to estradiol17 {J. Human cases in postmenopause were distributed equally into the 3 groups, however, many cases in premenopause belonged to the estradiol dependent group. The human cases were also classified into the 3 groups according to sensitivity to testosterone although not so definite. Hormonal treatments according to the sensitivity test were effective in all clinical cases.