Which marker is commonly used in breast cancer immunohistochemistry?

The estrogen receptor (ER) is a pivotal marker used in breast cancer immunohistochemistry because it plays a significant role in the biology and treatment of breast cancer. Breast cancers can be classified based on hormone receptor status, including ER-positive and ER-negative, which greatly influences prognosis and therapeutic decisions. Estrogen receptors are proteins found in some breast cancer cells that, when activated by estrogen, can promote cancer cell growth.

Identifying whether a breast cancer is ER-positive allows clinicians to determine the suitability of hormone therapies, such as tamoxifen, which can block estrogen from stimulating cancer growth. Therefore, ER status is vital for tailoring patient management and predicting treatment responses.

Other markers, while relevant in specific contexts, do not match the utility of the estrogen receptor in routine breast cancer assessments. For example, CD30 is primarily associated with certain lymphomas, Ki-67 is a proliferation marker indicative of tumor growth rate, and Beta-Catenin is involved in cell adhesion and signaling rather than directly guiding breast cancer therapy. Thus, ER stands out for its direct relevance in informing treatment strategies for breast cancer patients.