Radioimmunohistochemistry of epidermal growth factor receptor in breast cancer.
BACKGROUND
Conflicting reports of epidermal growth factor receptor (EGFR) expression in breast cancer and inconstant relationships with established prognostic indicators and outcomes suggest difficulties with EGFR measurement.


OBJECTIVE
To compare EGFR measurement in a panel of cell lines and in breast carcinomas by radioimmunohistochemistry (R-IHC), conventional immunohistochemistry (IHC), and a ligand binding (LB) assay.


METHODS
Eight EGFR-expressing cell lines and 50 primary breast carcinoma specimens were analyzed for EGFR by IHC, R-IHC, and LB assays. A further 153 primary breast cancer specimens were analyzed by R-IHC alone.


RESULTS
All 3 assays were in good agreement for the cell lines. In the subset of the 50 carcinoma specimens, EGFR was detected by LB assays in 19 (38%) and by IHC in 24 (48%). However, R-IHC detected EGFR in 46 (92%) of 50 and in 186 (92%) of all 203 carcinoma specimens. The LB assay agreed poorly with R-IHC of carcinomas, possibly because the LB assay is sensitive to EGFR-expressing nontumor breast parenchyma in the tissue analyzed. Both IHC and R-IHC on carcinoma specimens agreed better, but 26 carcinoma specimens (52%) in which EGFR was not detectable by IHC had a 10-fold range in receptor level detectable by R-IHC.


CONCLUSIONS
To elucidate the role of EGFR or other growth factor receptors in breast cancer requires accurate, sensitive receptor assays. With its dynamic range, R-IHC returned meaningful results over the entire range of expression actually present in breast cancer, which LB assays and IHC failed to do.
Robertson
Kevin W
KW
Lister Department of Surgery, Glasgow Royal Infirmary, Castle Street, Glasgow G31 2ER, Scotland, UK. KWRobertson@Compuserve.com
Reeves
Jonathon R
JR
Lannigan
Alison K
AK
Going
James J
JJ
Cooke
Timothy G
TG
Stanton
Peter D
PD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000737:chemistry*; D066246:ErbB Receptors / Q000032:analysis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes; D008875:Middle Aged; D011869:Radioligand Assay; D014407:Tumor Cells, Cultured
D007457:Iodine Radioisotopes; D066246:ErbB Receptors