[Progesterone receptors in breast cancer].

Levels of progesterone and estrogen receptors in tumor tissue were measured in 99 cases of stage I-IV breast cancer. 76.6% of tumors were found to be hormone-dependent. A considerable number of estrogen receptor-positive tumors lacked progesterone receptors. Tumors showing only progesterone receptors were not rare, either. The significance of the data obtained is discussed.