Hormone Receptor Assay

The hormone receptor assay is a laboratory test used to determine if cancer cells have receptors for certain hormones, such as estrogen and progesterone.

What is the purpose of the test?

The primary purpose of the hormone receptor assay is to help guide treatment decisions for patients with breast cancer or other types of cancer that may be influenced by hormones. The test results can help determine if a patient's cancer is likely to respond to hormone therapy.

How is the test performed?

The hormone receptor assay typically involves analyzing a sample of tumor tissue, usually obtained through a biopsy or surgery. The tissue sample is then sent to a laboratory where it is examined for the presence of estrogen receptors (ER) and progesterone receptors (PR).

Types of Hormone Receptor Assays

There are several types of hormone receptor assays, including:

• Immunohistochemistry (IHC): This is the most common method used to detect hormone receptors. IHC involves using antibodies that bind specifically to ER and PR proteins in the tumor tissue.
• Ligand-binding assay: This method measures the amount of hormone that binds to receptors in the tumor tissue.
• Reverse transcriptase polymerase chain reaction (RT-PCR): This method detects the genetic material (mRNA) that codes for ER and PR proteins.

Interpretation of Results

The results of the hormone receptor assay are typically reported as positive or negative, indicating whether the tumor cells have receptors for estrogen and/or progesterone. The results may also include a percentage of positive cells or a score that indicates the level of receptor expression.

Clinical Significance

The hormone receptor assay has significant implications for treatment decisions:

• ER-positive breast cancer: Patients with ER-positive tumors may benefit from hormone therapy, such as tamoxifen or aromatase inhibitors, which can help block the growth of cancer cells.
• PR-positive breast cancer: Patients with PR-positive tumors may also benefit from hormone therapy, although the response to treatment may be less predictable than for ER-positive tumors.
• ER-negative and PR-negative breast cancer: Patients with tumors that lack both ER and PR receptors may not respond to hormone therapy and may require alternative treatments, such as chemotherapy or targeted therapy.

Limitations and Potential Biases

The hormone receptor assay is a valuable tool for guiding treatment decisions, but it has some limitations:

• Tumor heterogeneity: The tumor tissue sample may not be representative of the entire tumor, which can lead to inaccurate results.
• Assay variability: Different laboratories and testing methods may produce varying results, which can affect treatment decisions.