Comparison of estrogen receptor and epidermal growth factor receptor content of primary and involved nodes in human breast cancer.

Estrogen receptors (ER) and epidermal growth factor receptors (EGFR) in the tumor cells of breast cancer tissues (primary tumors) and metastatic lymph nodes (involved nodes) were analyzed by immunocytochemical study in 19 patients; 12 were ER positive, and seven were ER negative. Microscopic study was used to determine the percentage of positive cells and the staining index. The percentage of EGFR-positive cells and the EGFR staining index were higher in the ER-negative primary tumors than ER-positive primary tumors. In ER-positive cases, both the number of ER-positive cells and ER content per cell was less in the involved nodes than in the primary tumors, whereas the number of EGFR-positive cells and EGFR content per cell was greater in affected nodes. On the other hand, in the ER-negative cases the number of EGFR-positive cells and EGFR content per cell remain almost unchanged between the primary tumors and involved nodes. The authors supposed a probability, in this study, that estrogen may exert inhibitory action on EGFR production through binding to ER.