Chemotherapeutic agents and estradiol receptor binding capacity

Cytotoxic agents used for the treatment of breast cancer did not inhibit the growth of uterus following estradiol injection to ovariectomized rats. They had no effect on the estradiol binding ability and on the dissociation constant of estradiol receptor binding of rat uterus. In addition, 1,2:5,6-dianhydrogalactitol, a highly active, proximal alkylating agent, applied in vitro did not alter the relative binding ability to tamoxifen to the cytoplasmic estradiol receptor of rat uterus and human breast cancer tissue. In summary, the present experiments did not reveal any disadvantageous interaction between simultaneously administered hormonal and cytotoxic drugs.