Analysis of estradiol and progesterone receptors in early and advanced breast tumors.

Estradiol receptor (RE) and progesterone receptor (RP) contents of primary human breast tumors are markedly influenced by histologic grade of the tumor. As the tumor becomes more anaplastic, there is an increase in the proportion of RE negative, RP negative tumors at the expense of the RE positive, RP positive group. Evidence is presented to suggest that some RE positive, RP negative tumors from postmenopausal women lack RP because of estrogen deficiency. The inclusion of RP assays increases the clinical usefulness of receptor assays in predicting response to hormone therapy for the advanced disease. Preliminary evidence suggest that RE and RP assays on the primary tumor may indicate the hormone sensitivity of subsequent metastatic disease.