What is IHC and How Does it Work?

Video Transcript

Cancer is a disease that happens at the cellular level. It occurs when cells in an area of the body begin growing and multiplying too rapidly.


Our cells produce many different types of proteins within them and on their surface. Proteins can have several functions: some proteins provide structure to the cell, signaling proteins allow the cell to communicate and respond to its external environment, and enzymes are proteins that control cellular metabolism. Cancer is the result of mutations in the genome that change the function or amount of specific proteins. The change in function and or quantity of these proteins cause cancer to grow.


Immunohistochemistry, or IHC, is a common laboratory test used to diagnose cancer. IHC utilizes modified antibodies that recognize and bind to specific proteins in and on the cell. Pathologists use these antibodies to “stain” specific proteins on the tissue biopsied from a tumor. The combination of different stains allows the pathologist to diagnose the tumor with a high degree of accuracy.


In addition to diagnosing tumors, IHC is used to identify protein biomarkers that guide therapy selection for oncologists. The abundance or presence of certain proteins indicate a tumor may be sensitive to specific drugs. A common example is found in breast cancer, which is divided into three major categories solely based on IHC results.

ER/PR positive breast cancer informs the oncologist that the tumor is sensitive to hormone therapies that act on the Estrogen and Progesterone Receptors.

HER2 positive breast cancer means there is an abundance of the HER2 protein on the surface of the cell and informing doctors that therapies targeting this protein could be effective.

Finally, Triple Negative Breast Cancer indicates the absence of ER, PR and HER2 on the tumor. These tumors benefit from additional molecular testing like DNA and RNA sequencing to identify other biomarkers to guide therapy.

Caris Life Sciences is a company dedicated to fighting cancer smarter, by using our advanced tumor profiling approach to better understand cancer at a molecular level. By testing DNA, RNA and proteins we are able to identify specific mutations and recommend personalized cancer treatment for each patient.

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Patient Education Videos

The Central Principles of Molecular Biology video series is meant to help explain molecular profiling and cancer, so that you can understand how Caris molecular profiling helps fight cancer through precision oncology.