[The influence of endogenous hormones on the oestrogen and progesterone receptor determination in tissue of mammary carcinoma (author's transl)].

Oestrogen and progesterone receptors were determined in 48 primary tumors of invasive mammary carcinoma. 86% showed a positive oestrogen receptor binding, 53% were progesterone receptor positive. The binding capacity for oestradiol was 5-211 pmoles/g tissue protein, for progestin (R 5020) 7-146 pmoles. The question of the investigation was whether the content of determined receptors depends on endogenous oestradiol and progesterone concentrations. A clear dependence did not exist between the hormone level in the plasma, collected just before the excision of the tumor, and the amount of identifiable receptors in the tumor. On the contrary, in considering the quantities of endogenous hormones in the tissues, based on the plasma content of the tissue and the plasma hormone level, a correlation could be found. The content of identifiable receptors decreased with increasing amounts of endogenous hormones in the cytosol. It is postulated that rather the amount of endogenous hormones in the tissue than the plasma hormone level characterizes the degree of saturation of existing receptors by endogenous hormones. Apparently, the determined receptor concentrations at endogenous hormone values under 2 pmoles/g tissue protein reflect rather the true receptor content, whereas at higher values too low or false negative results should be reckoned with.