Which test determines ER and HER2 status?

Which test determines ER and HER2 status?

• A. PCR
• B. FISH
• C. Immunohistochemistry (IHC)
• D. Blood test

Answer: (C)

In breast cancer, receptor status guides therapy, and the test used on tumor tissue to determine both estrogen receptor (ER) and HER2 status is immunohistochemistry. Immunohistochemistry stains tumor cells with antibodies against ER and against HER2, revealing whether these receptors are present and at what level. ER positivity is shown by nuclear staining, indicating that endocrine therapies (like tamoxifen or aromatase inhibitors) are appropriate. HER2 status is based on membrane staining intensity and completeness, scored from 0 to 3+. A strong 3+ result supports HER2-targeted therapy; a 2+ result is equivocal and typically prompts a reflex test with FISH to assess HER2 gene amplification. PCR or a simple blood test do not measure the receptor proteins on tumor cells in tissue, and thus aren’t used for determining ER or HER2 status. This approach directly informs treatment decisions by identifying tumors that will most likely respond to hormone therapy or HER2-targeted therapy.

In breast cancer, receptor status guides therapy, and the test used on tumor tissue to determine both estrogen receptor (ER) and HER2 status is immunohistochemistry. Immunohistochemistry stains tumor cells with antibodies against ER and against HER2, revealing whether these receptors are present and at what level. ER positivity is shown by nuclear staining, indicating that endocrine therapies (like tamoxifen or aromatase inhibitors) are appropriate. HER2 status is based on membrane staining intensity and completeness, scored from 0 to 3+. A strong 3+ result supports HER2-targeted therapy; a 2+ result is equivocal and typically prompts a reflex test with FISH to assess HER2 gene amplification. PCR or a simple blood test do not measure the receptor proteins on tumor cells in tissue, and thus aren’t used for determining ER or HER2 status. This approach directly informs treatment decisions by identifying tumors that will most likely respond to hormone therapy or HER2-targeted therapy.