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Research

Prognostic Biomarkers

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ER by IHC

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ER belongs to a superfamily of nuclear hormone receptors. It functions as a transcription factor when activated by its ligand estrogen and plays a key role in regulating growth, differentiation and tumorigenesis in breast. There are two known isoforms of estrogen receptor: ERα and ERβ. The current assays in clinical breast cancer measure only ERα. Nearly all the laboratories today measure ER by immunohistochemistry. For more information see ER by IHC.

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PR by IHC

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PR belongs to a superfamily of nuclear hormone receptors. ER induces PR expression, and therefore PR status serves as an indicator of an intact ER pathway. There are two known isoforms of PR: PR-A and PR-B. The current assays in clinical breast cancer measure both isoforms. Nearly all the laboratories today measure PR by immunohistochemistry. For more information see PR by IHC.

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Ki-67 Proliferation Index

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Proliferation index is an important prognostic factor in breast cancer. The Ki-67 protein is expressed in all phases of the cell cycle except G0 and serves as a good marker for proliferation. Studies that have evaluated proliferation index by K-i67 IHC in breast cancer have shown a significant correlation between high proliferation rates and shorter disease free and overall survival(1-4). For more information see Ki-67 Proliferation Index.

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HER2/neu by IHC

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The proto-oncogene HER-2/neu (c-erbB-2) resides on chromosome 17q and encodes a trans-membrane tyrosine kinase growth factor receptor. Amplification of the HER-2/neu gene, or overexpression of the HER-2/neu protein, is found in 20-30 percent of breast cancers. Amplified or overexpressed HER-2/neu is a weak unfavorable prognostic factor in untreated breast cancer patients. The predictive implications of HER-2 alterations are more complex and include resistance to hormonal therapy (1, 2), resistance to CMF chemotherapy (3, 4), responsiveness to doxorubicin (5-7), and responsiveness to Trastuzumab (Herceptin®) therapies (8, 9). The primary indication for assessing HER-2/neu today is to identify patients who might benefit from trastuzumab therapy.

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HER2/neu by FISH

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The proto-oncogene HER-2/neu (c-erbB-2) resides on chromosome 17q and encodes a trans-membrane tyrosine kinase growth factor receptor. Amplification of the HER-2/neu gene, or overexpression of the HER-2/neu protein, is found in 20-30 percent of breast cancers. There is a greater than 90 percent correlation between gene amplification and protein overexpression. Some studies suggest that HER-2 gene amplification assessed by Fluorescent In Situ Hybridization (FISH) may improve the predictive ability of this marker for Trastuzumab (Herceptin®) therapies (1, 2), especially in the 10-20 percent of cases with equivocal (i.e. 2+) results for protein expression by IHC . The primary indication for assessing HER-2 by FISH today is in cases with equivocal IHC results (3, 4).