Expression of c-erbB-2 oncoprotein in primary human tumors: an immunohistochemistry study.

An immunohistochemical study was performed with 130 primary malignant human tumors of breast (n = 55)..colon/rectum (n = 16), stomach (n = 19), esophagus (n = 14), lung (n = 15) and liver (n = 11) using the 21N c-erbB-2 specific monoclonal antibody to identify the tumors that over-expressed the c-erbB-2 oncoprotein. Positivity appeared as an intense brown granular staining located predominantly at the cell membrane. This occurred in 41.8% of breast carcinomas, 12.5% of colorectal adenocarcinomas. None of the gastric adenocarcinomas, squamous cell carcinomas of the esophagus, small cell lung carcinomas or hepatocellular carcinomas were positive for the oncoprotein. The result of this study suggests that over-expression of the c-erbB-2 oncoprotein is common in breast cancer and relatively rare in other malignancies examined.