[What can be now expected of the determination of estrogen and progesterone receptors in the treatment of breast cancers].

Since the first published correlations around the years 1975 between estrogen and progesterone receptors and response to hormone therapy, numerous data have modified our insight on hormone dependency. For instance, it is now well established that tumors are not "receptor positive" or "receptor negative" but contain variable receptor quantities synthesized by a more or less important fraction of tumor cells. This allows to better understand events leading to partial response or to relapse. Receptor detection by classical assays gives no indications on receptor functionality, and data from molecular biology have shown that mutated receptors exist that have lost their property to induce genes, or that present new acquired properties. Nevertheless, these functional modifications are rare, and must not mask a reality: 75 to 80% of tumors with high receptor levels respond to hormone therapy, and the clinician must take this fact into account in three situations: for adjuvant therapy, for metastasis therapy, and for some special cases of difficult diagnosis.