Hormone receptor status test

Estrogen and progesterone are female hormones. They can stimulate the growth of some cells, including breast cancer cells. Normal breast cells and some types of breast cancer cells have estrogen receptors (ER) and progesterone receptors (PR) on their surface or inside (in the nucleus or other parts of the cell). These receptors are where the hormones attach to the cells. Once they are attached, the hormones can affect the behaviour or growth of the cells.

Breast cancer cells that have ER and PR receptors need these hormones to grow and divide.

Hormone receptor testing is done at the time of diagnosis for breast cancer or when breast cancer comes back after treatment (recurs).

Hormone receptor status testing is often done at the same time as the HER2 status test.

Knowing the hormone receptor status of the tumour helps doctors predict how well hormonal therapy will work and what other treatments may be effective. Hormone receptor status also affects prognosis and survival for breast cancer.

This test can be used for both women and men who have breast cancer. Men have smaller amounts of estrogen and progesterone than women, but this test can still help plan their treatment.

Hormone receptor status testing is done on a tissue sample taken with a biopsy. The tissue is examined using immunohistochemistry tests to identify the number of hormone receptors in the breast cancer cells.

Results of the test are based on whether or not there are any receptors of each type and how many are found. The results are reported as positive or negative. A tumour may be a combination of positive (+) and negative (–) receptors.

In about two-thirds of all cases of breast cancer, the tumour has receptors for estrogen, progesterone or both. Breast cancer that is ER negative and PR positive is very rare, and more testing may be needed to be sure about the status.

Hormone status tells doctors if hormonal therapy is likely to slow or stop the cancer cells from growing. This helps them decide if hormonal therapy is a treatment option for you:

• ER-positive tumours and tumours that are both ER and PR positive are often treated with hormonal therapy.
• ER-negative PR-positive tumours are sometimes treated with hormonal therapy.
• Tumours that are hormone receptor negative (ER– and PR–) are not treated with hormonal therapy.

Sometimes breast cancer may come back, or recur, after it has been treated. A biopsy of tissue from a tumour may be done to confirm the diagnosis of breast cancer recurrence or to rule out a new primary breast cancer. Hormone receptor status may be re-checked at this time.

Women whose first tumours were ER-positive may develop ER-negative tumours when cancer comes back. This is an important prognostic factor because additional hormonal therapy may not work as well for these tumours.

Breast cancer may respond to hormonal therapy if the recurrence is several years after the first diagnosis of breast cancer and the first tumour was hormone receptor negative.