Estriol binding in uterine corpus cancer and in normal uterine tissues.

1. The specific bindings of estriol (E3) and estradiol-17 beta (E2) to their specific receptors were investigated in endometrial carcinoma from 7 patients and normal tissues from their respective organs or from other patients. 2. In both cytosolic and KCl-extracted fractions from them, specific binding sites for E3 and E2 were detected, demonstrating the presence of their separate receptors in human uterus-associated tissues. 3. In certain cases (6 cases) of well-differentiated adenocarcinoma, the ratio of concentration of E3 receptor to that of E2 receptor was almost equal to or higher than in other normal tissues. 4. These findings of unique localization of E3 receptor distribution may offer new insight into identification of endometrial carcinoma more likely to respond to hormonal influence or therapy.