Short-term tissue culture of human breast cancer: presence of estrogen receptors and 17 beta-estradiol stimulation of RNA synthesis.

The stimulation of RNA synthesis induced by estradiol has been studied on 60 breast cancers in short-term cultures. In the same tumors the estrogen receptor (ER) assay was carried out. In 35% of the cases studied the stimulating effect by estradiol in vitro was observed. The frequency of response to in vitro hormone treatment was higher (42%) in ER+ cancers and lower (25%) in ER- cancers. The specificity of the in vitro test was assessed by the use of tamoxifen.