Relationships between steroid receptor and epithelial cell proliferation in benign fibrocystic disease of the breast.

Tissue specimens from 27 patients with mammary fibrocystic disease were assayed for estrogen (ER) and progestin (PR) receptors. Seventeen patients (63%) had ER-positive lesions (greater than 5 fmol/mg protein). A progression in ER presence was noted from fibrocystic disease (35%) and fibrosing adenosis (50%) to lobular and ductal hyperplasia (85%). Similarly, ER content increased from 14.5 +/- 13 fmol/mg cytosol protein in fibrocystic disease and fibrosing adenosis to 31.5 +/- 23 fmol/mg protein in epithelial hyperplastic lesions. Furthermore, the ER-PR couple was only encountered in lobular and ductal hyperplasia. The authors' data indicate that the incidence of steroid receptor parallels the intensity of hyperplasia in benign breast disease.