Quantitative radioimmunohistochemical measurements of p185(erbB-2) in frozen tissue sections.

Abstract

The relationship between expression of the c-erbB-2 proto-oncogene and the biology of breast cancer has been investigated widely, most studies using immunohistochemistry in formalin-fixed, paraffin-embedded tissues. This technique is at best semiquantitative and there is a high degree of interstudy variability because of its subjective nature and poor methodological standardization. The relationship between the levels of expression and biology can be examined thoroughly only with an accurately quantitative technique. We have developed a radioimmunohistochemical assay to measure p185(erbB-2) in tissue biopsy specimens. The method involves incubating frozen sections with 125I-labeled monoclonal antibody, microautoradiograpy, and grain counting with image analysis. Sections of cell pellets with known c-erbB-2 levels are processed with each batch of samples as internal calibration standards. We have quantified c-erbB-2 expression in 60 breast carcinomas and compared the results with conventional immunohistochemistry. Radioimmunohistochemistry measured receptor levels throughout the range of expression in breast carcinomas, whereas conventional immunohistochemistry detected the protein only in the highest expressing tumors. The quantitative, objective data produced by radioimmunohistochemistry allow a more thorough evaluation of the relationship between c-erbB-2 expression and tumor biology. This technique may have applications in other fields where quantitative data is required and relevant monoclonal antibodies are available.

The clinical evaluation of HER‐2 status: which test to use?

“…The lack of standardization of these immunohistochemical methods accounts, in large part, for the fact that overexpression of HER‐2 in breast cancers is reported in anywhere from 5% to 85% of all cases and errors relating to antibody selection, fixation, and interpretation have been widely documented 16, 33–36. Only a very small number of reports have made any attempt to quantify HER‐2 expression accurately and objectively, since, in the absence of an endogenous HER‐2 ligand, this method requires the use of antibodies as surrogate ligands 3, 4. Furthermore, analyses of tumour samples are often based on the assumption, often false, that all the material present represents tumour cells.…”

“…Overexpression of the p185HER‐2 protein product of HER‐2/ neu is closely related to gene amplification in breast cancer 1–4. Slamon et al first described the biological importance of HER‐2 in breast cancer in 1987 1 and many subsequent publications have confirmed the prognostic significance of HER‐2 amplification and overexpression in breast cancer 5–13.…”

A new hypothesis on the role of c-erbB2 oncogene in the progress of breast cancer

“…No c-erbB2 was detected in 15% tumors. Clinical studies showed that the prognosis was the worst for tumors with c-erbB2 gene amplification and tumors without c-erbB2 protein in comparison with 60% tumors with only overexpression of c-erbB2 oncogene [8].…”

HER-2/neu in Breast Cancer

“…[21][22][23][24] Nevertheless, there are rare cases described in the literature that do not show protein expression (0 and 1+) but present gene amplification. 25 According to our results, 0 and 1+ cases can be definitely considered negative without FISH confirmation, given the perfect concordance between the two methods.…”