201. Tissue Array Technology for Testing Interlaboratory and Interobserver Reproducibility of Immunohistochemical Estrogen Receptor Analysis in a Large Multicenter Trial
- Author
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Hans Konrad Müller-Hermelink, Michael Mengel, Thomas Rüdiger, Hans Kreipe, Birgitt Wiese, and Reinhard von Wasielewski
- Subjects
Observer Variation ,Pathology ,medicine.medical_specialty ,Paraffin Embedding ,Tissue Fixation ,Tissue microarray ,business.industry ,Mammary gland ,Reproducibility of Results ,Estrogen receptor ,General Medicine ,Laboratories, Hospital ,Antiestrogen ,Immunohistochemistry ,Staining ,medicine.anatomical_structure ,Receptors, Estrogen ,Germany ,Progesterone receptor ,medicine ,Humans ,Female ,Receptor ,business - Abstract
Semiquantitative immunohistochemical assessment of estrogen receptor (ER) is used to predict the likelihood of response to antiestrogen therapy in breast carcinoma. If semiquantitative immunohistochemical analysis leads to therapeutic decisions, the importance of standardization and quality control increases. ER assessment reproducibility was studied among 172 laboratories using tissue microarray slides with 20 tissue spots negative and 10 tissue spots expressing ER at low, medium, or high levels. More than 80% of the laboratories demonstrated ER positivity in the medium- and high-expressing tissue spots, but only about 43% succeeded with tissue spots with low expression. Poor interlaboratory agreement was based on insufficient retrieval efficacy as shown by additional tests using autoclave pretreatment. The immunohistochemical scores used to quantify therapeutic target molecules remain inconclusive as long as progress toward standardized immunohistochemical procedures and evaluation is not achieved. Tissue microarray technology has proved its suitability for large-scale immunohistochemical trials, giving rise to new dimensions in control assessment. Immunohistochemical stains have become an indispensable part of laboratory procedures in pathology, both for diagnostic and research purposes. In the past, immunohistochemical analysis was used mostly for qualitative assessments, eg, lineage-specific markers such as antibodies against keratin were applied to determine the epithelial origin of a tumor. Today, a growing number of markers are used that identify cell cycle–dependent proteins, receptors, oncogenes, and antioncogenes, even in fixed tissue. However, many of these require a semiquantitative evaluation to establish the degree of expression. Antiestrogen receptor antibodies were among the first markers introducing such a semiquantitative immunohistochemical assessment, followed by others such as progesterone receptor (PR) or HER2 (c-erbB2). Several methods are known (eg, immunoreactive score [IRS], H score, quick score) for reporting estrogen receptor (ER) and PR results to clinicians. The IRS system is widely used in Germany. It is calculated by multiplication of the number of positively labeled cells (4 percentage groups) with the intensity of the staining
- Published
- 2002