Breast Center Pathology Laboratory
SERVICES/RESOURCES - CLINICAL
Prognostic Biomarkers
ER by IHC
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.
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PR by IHC
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.
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Ki67 by IHC
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 Ki-67 IHC in breast cancer have
shown a significant correlation between high proliferation rates
and shorter disease free and overall survival(1-4). More
HER2/neu by IHC
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% 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
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% of breast cancers. There is a greater
than 90% 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% 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). More