Histochemical tumor markers for evaluation of hormone dependence in breast cancer

Lectin from the peanut (peanut agglutinin = PNA) possesses a high affinity for D-galactosyl-(1-3)-N-acetyl-D-galactosamine, used for histochemical investigations on formalin-fixed tissue sections of normal mammary gland as well as of benign and malignant breast diseases. Thereby, a lectin-binding pattern was found that partly exhibited secretory malfunction. Additional studies with a labeled antibody directed against a milk fat globule membrane glycoprotein, which was isolated by PNA affinity chromatography from human milk, confirmed the PNA receptor as a marker of a milk protein in breast carcinomas. The most important clinicopathological finding, however, was that in accordance with the secretory activity about 77% of PNA-positive tumors responded to endocrine treatment, whereas PNA-negative mammary carcinomas usually failed to show any response to hormonal therapy. These results also correlated with the hormone receptor content of tumor tissue.