RELATIONSHIP BETWEEN LOW ESTROGEN-RECEPTOR VALUES AND OTHER PROGNOSTIC FACTORS IN PRIMARY BREAST-TUMORS

Background. The current study compared the immunocytochemical expressi on of estrogen (ER) and progesterone (PgR) receptors by malignant brea st cells to the hormone receptor concentrations reported from radiolig and assays. These values were examined in relation to DNA ploidy and t he fraction of cells in S phase.Methods. ER and Pp li concentrations, DNA ploidy, and S-phase fractions were measured by standard techniques with 124 samples of invasive ductal carcinoma. Suspensions of tumor c ells were examined by immunocytochemical assay (ICA) for the percentag es of ER and PgR positive cells. Results. Twenty-six of the 38 tumors from patients 50 years of age or younger were classified as high S-pha se fraction, and 28 tuners had aneuploid levels of DNA. The 20 ER posi tive tumors each contained less than 100 fmol/mg. Thirty-nine of the 8 6 tumors from patients older than 50 years were classified as high S p hase, and 41 were aneuploid. Sixty-five samples were considered ER pos itive by radioligand assay. ICA showed that tumors in either age group with less than 40 fmol/mg did not contain EX positive cells. The prop ortion of samples with PgR levels between 10 and 100 fmol/mg was small , and fewer PgR positive tumors were categorized as negative wizen exa mined by ICA for receptor containing cells. The reclassification of th e hormone receptor status of a tumor based on ICA appeared to be indep endent of S-phase and ploidy values. Conclusions. Tumors that are clas sified as ER or PgR positive based on accepted cutoff values Snr radio ligand assays may actually be receptor negative because the tumors do not appear to contain receptor positive cells.