One important test that will be performed on your tumor will determine the “Hormone Receptor Status” of your disease. This will help your doctor determine if there are any additional treatments (hormone therapy) you may receive to help protect you from a recurrence. If your hormone receptor status is positive for ER, PR or HER2, you will most likely be offered an additional measure of protection in the form of pill you take once a day for five years. Many metaplastic breast cancer patients are negative for reactivity to these hormones and would not benefit from hormone therapy.
Nearly two-thirds of breast cancer cells will test positive for hormone reactivity. An estrogen (ER) or progesterone (PR) positive result means that the cancer cell is being fueled by these hormones. This discovery allowed researchers to target this action in the body in an attempt to turn off this reaction. Researchers were able to create drugs that suppress the effects of ER and PR on the cancers cells, thus stopping or slowing their growth. So being positive for this reaction means that additional drugs, like tamoxifen, are available for you to take after your other treatments end. These drugs include Tamoxifen, Evista, Arimidex and Aromasin. Your menopausal status plays a role in which drug you may be offered.
HER2 is somewhat similar in that researchers have found an effective means for treating women with HER2 positive cancer cells. HER2 is the Human Epidermal Growth Factor Receptor 2. It is a protein that, like estrogen and progesterone, effects the growth of some breast cancers. HER2 is found to be over-expressed in about 15-20% of breast cancers. The drug Herceptin is available for women who are HER2 positive.
The vast majority of women with metaplastic breast cancer are triple negative, that is… they are not positive for ER, PR or an over-expression of HER2. Metaplastic breast cancers with positive reactions to ER, PR or HER2 are less common and usually only slightly reactive. Triple negative cancers are considered more difficult to treat and tend to be more aggressive. The main issue for women with triple negative breast cancers is that there are no hormone therapy drugs to slow or stop the chances of recurrence.