Receptors: Estrogen, Progesterone & HER2/neu

In addition to determining the pathology of the breast cancer, the tissue will also be analyzed for so called "receptors." These are molecules on the surface of cells or in the inside of cells that recognize certain hormones and proteins that circulate in the blood. The most common receptors that are studied are estrogen, progesterone and HER2/neu receptors.

A simple way of thinking about receptors is to visualize a lock and key. The lock represents the receptor. The key represents the chemical that fits into the lock, unlocks the lock and allows entry into the cell. In this case, entry will be into the center of the cell where the cell is instructed to grow.

If the receptor is present on the cancer cell, doctors will use medicines that will try to prevent the lock from being unlocked by the naturally occurring chemical that would normally unlock it, and thus prevent the instructions to the cell to continue to grow.

Cancer cells that have these receptors are described as estrogen-receptor positive (ER positive) and progesterone-receptor positive (PR positive). Cancer cells that don't have them are described as ER and PR negative.

Your pathology report will state whether your cancer cells have estrogen or progesterone receptors. These receptors will help determine what type of treatment should be offered to the patient.

Estrogen and progesterone, the "female hormones," circulate in the body of women. They are needed for normal growth, development and proper function of the breasts. However, estrogen and progesterone can also contribute to the development of breast cancer, specifically hormonally responsive breast cancer.

Many breast cancer cells will have estrogen receptors, progesterone receptors or both. The presence of one or both types of receptors helps predict if the cancer will shrink by giving medicines that block the receptors. For example, the growth of cells with estrogen receptors can be slowed or stopped by the use of SERM drugs, such as tamoxifen, which block the cells' receptors from receiving estrogen. If the breast cancer cells are ER and PR negative, hormonal receptor blockers will probably have less ability to stop or slow down cancer growth.

The HER2/neu receptor is a new chemical (using our example, a new lock) that has been discovered on breast cancer cells. If present, it indicates that the growth of the breast cancer may be dependent upon a specialized chemical in the blood. About 25%-30% of breast cancer cells have too much HER2/neu. Because this protein stimulates cancer cell growth, cancer cells that overproduce HER2 tend to spread more aggressively than those with normal amounts of the protein. Medicines, such as Herceptin, can block the effect of this chemical on the growth of breast cancer cells.

This method of determining what is on the breast cancer has provided a great deal of excitement for the treatment of breast cancer. Doctors are now better equipped to help decide with more precision what medicines should be selected for treatment and therefore maximizing the likelihood of selecting treatments that will be effective and successful.

Next >> Treating Breast Cancer

In This Article:
Diagnosing Breast Cancer
Tumor Staging and Tumor Margins
Invasive Cancer Grading
Receptors: Estrogen, Progesterone & HER2/neu

From the Harvard Health Publications Special Health Report, Breast Cancer: Strategies for Living. Copyright 2004 by the President and Fellows of Harvard College. Illustrations by Harriet Greenfield, M.A., and Jesse Tarantino. All rights reserved. Used with permission of StayWell. Harvard Medical School does not endorse products.
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