Estrogen receptor test

Test to determine the presence of estrogen receptors in tissue

Estrogen Receptor Test

The estrogen receptor test is a laboratory test used to determine the presence of estrogen receptors (ER) in tissue samples, most commonly in breast cancer tissue. This test is crucial in guiding the treatment of breast cancer, as the presence of estrogen receptors can influence the choice of hormonal therapy.

Diagram showing tumor growth

Background

Estrogen receptors are proteins found inside and on the surface of certain cells, including breast cancer cells. These receptors bind to the hormone estrogen, which can promote the growth of cancer cells. The presence of estrogen receptors in cancer cells is a key factor in determining the behavior of the cancer and its response to treatment.

Procedure

The estrogen receptor test is typically performed on a sample of tumor tissue obtained through a biopsy or surgery. The most common method used is immunohistochemistry (IHC), which involves staining the tissue with antibodies that bind specifically to estrogen receptors. The stained tissue is then examined under a microscope to assess the presence and quantity of estrogen receptors.

Interpretation

The results of the estrogen receptor test are usually reported as a percentage of cells that test positive for estrogen receptors. A tumor is considered "ER-positive" if a significant proportion of the cells contain estrogen receptors. This information is used to predict the tumor's response to endocrine therapy, such as tamoxifen or aromatase inhibitors.

Clinical Significance

ER-positive breast cancers are more likely to respond to hormonal therapies that block estrogen's effects or lower estrogen levels in the body. These therapies can slow or stop the growth of ER-positive tumors. In contrast, ER-negative tumors do not rely on estrogen for growth and are less likely to respond to hormonal treatments.

Related Pages

• Breast cancer
• Hormonal therapy (oncology)
• Immunohistochemistry
• Tamoxifen
• Aromatase inhibitor