What is the most common immunohistochemical (IHC) tumor marker?

The most common immunohistochemical tumor marker is the estrogen receptor-positive marker. This marker is essential in breast cancer diagnostics because it helps determine whether cancer cells grow in response to estrogen. Testing for estrogen receptors in breast tissue is a routine part of evaluating breast cancer, as it has implications for treatment planning and prognosis. Tumors that are estrogen receptor-positive may respond well to hormone therapies, such as tamoxifen, which target these receptors.

In clinical practice, the identification of estrogen receptor status is crucial because it not only aids in understanding the biology of the tumor but also assists oncologists in formulating tailored treatment strategies based on whether the tumor is hormone-sensitive. The prevalence of this marker in breast cancer, as well as its significance in shaping therapeutic decisions, establishes it as the most common IHC tumor marker used in clinical oncology.