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Estrogen and Progesterone Testing in Breast Cancer

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The Panel recommends that ER and PgR status be determined on all invasive breast cancers and breast cancer recurrences. A testing algorithm that relies on accurate, reproducible assay performance is proposed.

I was surprised to find that, because up to twenty percent of tests for estrogen and progesterone positivity and negativity have been found to be innacurate, new guidelines have been established for how these tests are conducted.  It never occurred to me that there was any doubt as to accuracy.  Many treatments for breast cancer are based on these results.
I hope these new guidelines will be more reliable since they are incredibly important.  I can only assume that my tests in 2003 were accurate, although they were not typical.
Mary Miller- Breast Cancer Profile in Courage
PURPOSE: To develop a guideline to improve the accuracy of immunohistochemical (IHC) estrogen receptor (ER) and progesterone receptor (PgR) testing in breast cancer and the utility of these receptors as predictive markers.
METHODS: The American Society of Clinical Oncology and the College of American Pathologists convened an international Expert Panel that conducted a systematic review and evaluation of the literature in partnership with Cancer Care Ontario and developed recommendations for optimal IHC ER/PgR testing performance.
RESULTS: Up to 20% of current IHC determinations of ER and PgR testing worldwide may be inaccurate (false negative or false positive). Most of the issues with testing have occurred because of variation in pre-analytic variables, thresholds for positivity, and interpretation criteria.
RECOMMENDATIONS: The Panel recommends that ER and PgR status be determined on all invasive breast cancers and breast cancer recurrences. A testing algorithm that relies on accurate, reproducible assay performance is proposed. Elements to reliably reduce assay variation are specified. It is recommended that ER and PgR assays be considered positive if there are at least 1% positive tumor nuclei in the sample on testing in the presence of expected reactivity of internal (normal epithelial elements) and external controls. The absence of benefit from endocrine therapy for women with ER-negative invasive breast cancers has been confirmed in large overviews of randomized clinical trials.
PMID: 20586616

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