Immunohistochemistry (IHC) Markers In Breast Cancer

March 16,2022
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Immunohistochemistry (IHC) is used for diagnostic problems with breast biopsies. IHC is also frequently used as prognostic and predictive tests.

IHC Marker(s)	Purpose	Cell/ antigen/ protein targeted	Interpretation
ER, PR, Her2	Predictive/ Theranostic	Hormonal markers	Immunohistochemical stains for ER, PR, and HER2 are performed for predictive and therapeutic information.
Ki-67	Prognostic	Proliferative index marker	Used to determine the prognosis of breast cancer. Also seen in differentiating Phyllodes tumour - benign, borderline, and malignant.
P63, Calponin, SMA, S100, HMWCK (high molecular weight cytokeratin)	Diagnostic	Myoepithelial cells	The presence of myoepithelial cells (MECs) in an intimate relationship with the epithelial cells of the lesion determines the difference between in-situ and invasive disease and between benign pseudo-invasive lesions and invasive carcinoma. Also used to categorize various papillary lesions of the breast.
E-cadherin (ECAD)	Diagnostic	Cell adhesion molecule	Used to differentiate between lobular and ductal carcinoma. Ductal carcinomas (in-situ or invasive) retain membranous ECAD. Lobular carcinoma cells lose ECAD staining.
Cytokeratin, EGFR	Diagnostic	Basal-like carcinoma	Basal-like carcinomas are triple-negative and show immunoreactivity for basal cytokeratin and EGFR.
Cytokeratin	Diagnostic	Sentinel node metastasis	IHC for cytokeratin stains highlight isolated tumour cells (tumour cell aggregates ≤0.2 mm).
EMA, MUC-1	Diagnostic	Micropapillary carcinoma	Identifying special types of breast carcinomas - micropapillary carcinomas can be confidently identified using EMA (or MUC-1), which demonstrates reverse.
CK7, GCDFP15, Mammaglobin, ER, CK20	Diagnostic	Systemic metastasis of breast carcinoma	In cases of morphologically similar metastatic tumours, a panel of markers are used to confirm breast primary.
PDL-1	Predictive/ Theranostic	Immune checkpoint inhibitor	In triple-negative breast cancer if cells have high expression of PDL1, then immunotherapy can be advised.

Triple-Negative Breast Cancers (ER-negative, PR-negative, HER2-negative):

Studies suggest that triple-negative breast cancers present aggressively with rapid growth and have a poorer prognosis compared with patients with other breast cancer subtypes.
Triple-negative breast cancer is usually high grade, and the most common histology is infiltrating ductal carcinoma, although a rare histologic subtype, medullary carcinoma, is generally triple negative.
While the triple-negative clinical phenotype is heterogeneous, the basal-like molecular subtype comprises a large proportion, particularly for BRCA1-associated breast cancer.

Suburban Diagnostics offers a complete range of IHC and molecular testing for the diagnosis and prognostication of all types of breast cancers.

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