[Breast cancer. Development of the concentration of hormonal receptors under cytotoxic chemotherapy].

38 patients with locally advanced breast cancer, were treated with a program of cytotoxic chemotherapy including Adriamycin, Cyclophosphamide, 5 Fluoro-uracile and Prednisone. The concentration of hormonal receptors (Estrogen ER and Progesterone receptor PR) in the tumor were studied before starting the chemotherapy and after one to 9 courses of chemotherapy. This therapeutic response rate was not related to the initial level of ER and PR. After chemotherapy, we observed an increase of ER level in 14 cases out of 29 (59%), of PR level in 17 out of 32 cases (53%); A therapeutic response is observed in 11 cases out of 17 when the PR concentration is increased and in 3 cases out of 15 when the PR concentration was either stable or decreased. These observations let us to suppose a selective initial activity of chemotherapy on lesser differentiated tumor cells.