Are Hormone Receptors Present?

Receptors for the female hormones estrogen and progesterone are another key personality feature of breast cancer. You can read about whether these receptors are present in your pathology report. These receptors are the eyes and ears of the breast cells, getting messages sent by the hormones and figuring out what to do with these messages. The hormones will tell the receptors to stimulate or "turn on" breast cell growth. Estrogen and progesterone can increase both normal and abnormal breast cell growth.

Your doctor will order a hormone receptors assay, a test to see if the cancer is sensitive to estrogen and progesterone. If a tumor is estrogen-receptor positive (ER-positive), it is more likely to grow in a high-estrogen environment. ER-negative tumors are usually not affected by the levels of estrogen and progesterone in your body. This is one time when hearing the word "positive" may really mean something good (so often, a "positive" test result really means that something not so good was found).

ER-positive cancers are more likely to respond to anti-estrogen therapies. If you have an ER-positive cancer, you may respond well to tamoxifen, a drug that works by blocking the estrogen receptors on the breast tissue cells and slowing their estrogen-fuelled growth. A study suggests that Herceptin (chemical name: trastuzumab) may be beneficial regardless of your ER/PR status.

More information on tamoxifen.

If you've gone through menopause, you may think that you are no longer at risk for estrogen-fuelled cancer growth. That's not true. While your ovaries are no longer producing estrogen after menopause, your adrenal glands produce another hormone that is converted into estrogen by the body. That estrogen can still stimulate tumor growth. So estrogen is an important consideration even for women who have stopped menstruating.