Comparison of EGFR, c-erbB-2 product and ras p21 immunohistochemistry as prognostic markers in primary breast cancer.

In a prospective study of 75 breast carcinomas, monoclonal antibodies EGFR1, Anti-serum 21N (As21N) and RAP-5 were used to assess immunohistochemically expression of Epidermal Growth Factor Receptor (EGFR), c-erbB-2 oncoprotein and ras protein p21. A careful comparison was made of their relative prognostic significance. Positive staining was seen with EGFR1 in 12/71 cancers (17%) and with As21N in 16/75 cancers (21%). Positive staining with RAP-5 occurred in all cancers and benign breast tissue, but varied in intensity. EGFR expression correlated with the number of involved lymph nodes, histological grade, estrogen and progesterone receptor (ER, PR) levels and the Melbourne Prognostic Index. C-erbB-2 and ras expression both correlated with ER levels and EGFR, but not with the Prognostic Index. Based on an immunohistochemical technique, EGFR expression emerges as the parameter with strongest prognostic associations.