DNA content and estrogen receptors in primary carcinoma of the breast

DNA content and estrogen-receptor status were studied in 54 consecutive patients with primary breast carcinoma. Estrogen-receptor determinations were performed by immunohistochemical assay on frozen sections with a monoclonal antibody against the estrogen-receptor molecule and by biochemical analysis with a dextran-coated charcoal method. Nuclear DNA content was measured by flow cytometry performed on formalin-fixed, paraffin-embedded sections. Seventy-two percent of tumours were positive for estrogen receptors by immunohistochemical assay and 67% by biochemical assay. Comparison of the qualitative results of immunohistochemical and biochemical estrogen-receptor determinations revealed a strong correlation between the two assays, with agreement in 90% of the cases (p less than 0.001). Regression analysis showed only a weak relationship between the quantitative results of the two assays. DNA analysis was performed in 51 cases, and 54% demonstrated aneuploid stemlines by flow cytometry. An association was demonstrated between aneuploidy and low levels of estrogen receptor. The association was highly significant with the immunohistochemical assay but not with the biochemical assay. The authors' results suggest that immunohistologic determinations of estrogen receptor status may better reflect the biologic features of the tumour cells. However, improved standardization in reporting the results is necessary if the test is to have widespread use.