Progesterone receptor as a more reliable prognostic parameter than estrogen receptor in patients with advanced breast cancer.

Abstract

Sir, The prognostic significance of estrogen receptors (ER) in breast cancer is well documented (1, 2). As far as hormone dependence is concerned, the simultaneous presence of ER and progesterone receptors (PR) increases the sensitivity of the prediction. This fact points out the functional relationship between ER and PR in target tissues as the real parameter of hormonal dependence; consequently, PR appears as a more reliable index than ER in clinical applications. So far, very few trials have studied the prognostic significance of PR compared to ER in breast cancer (3). From a study starting June 1977, we report 102 cases of disseminated breast cancer treated in controlled trials with combinations of cytotoxic drugs. Before initiating the treatment, ER and/or PR levels were measured either on surgical samples or on drill-biopsies by the dextran-charcoal assay (4). ER were assayed in 91 cases, PR in 90 cases, ER and PR (simultaneously) in 79 cases. ER were positive (ER+) in 40 patients (44%), PR (PR+) in 26 cases (29%). Where both were measured together, both were positive in 21 cases (26%); both were negative in 44 cases (56%). Sixty-two per cent of E R + versus 41% of E R patients survived beyond 18 months (p = 0.03). By contrast, 73~ of P R + versus 40~ of P R patients survived beyond 18 months (p = 0.008) (see Fig. 1). In those patients where ER and PR could be simultaneously obtained (79 cases), the survival of the small ER + P R subgroup did not differ from that of E R P R patients. These results emphasize the more reliable significance of PR as a prognostic parameter, which therefore should be assayed in priority when tissue sampling is limited. H. Magdel6nat P. Pouillart M. Jouve T. Palangi~ E. Garcia Giralt Institut Curie, 26, rue d'Ulm, B. Bretaudeau 75231 Paris, Cedex 5, France B. Asselain v