Expression of epidermal growth factor receptor (EGFR) in breast cancer as related to clinical, prognostic and cytometric factors.

A series of 213 female breast carcinomas were analysed immunohistochemically for the expression of epidermal growth factor receptor (EGFR), with special emphasis on its possible prognostic significance. A total of 114/213 tumors (53.5%) were EGFR positive. EGFR was almost exclusively expressed in the cytoplasm of the cancer cells, but in a few cases, the cell membranes showed EGFR positive staining as well. EGFR expression was related to the histological grade of the tumours in that a linear decrease of the staining was found in parallel with the decreasing tumour differentation (P = 0.024). On the other hand, axillary lymph node status (P = 0.95), histological type (P = 0.60), tumor size (P = 0.87), DNA-index (P = 0.56), S-phase (P = 0.80), mitotic index (P = 0.72), or estrogen (ER) and progesterone receptor (PR) content (P = 0.45) did not show any statistical correlation with the EGFR expression. EGFR positivity as an independent factor, had little (if any) effect on the patients prognosis. Tumor size (P = 0.004), axillary lymph node involvement (P = 0.024) and PR positivity (P = 0.008) were the single most significant prognostic factors in multivariate survival analysis. The results indicate that, in clinical breast cancer, immunohistochemical assessment of EGFR provides no prognostic information additional to the well established prognostic factors.