What is Estrogen Receptor-Positive Breast Cancer?

wiseGEEK Writer

Estrogen receptor-positive breast cancer refers to the forms of breast cancer that contain estrogen receptors. In the presence of estrogen, these cancers can grow more significantly. About two-thirds to three-fourths of all types of breast cancer are considered estrogen receptor-positive, and this is actually an encouraging thing in the treatment of this condition. While these cancers may grow more quickly with continued exposure to estrogen, they can also respond better to treatments that shut off or bind the receptors against receiving the hormone. Understanding this connection has led to improved survival rates for women, provided cancer detection is early.

Following a lumpectomy, an estrogen receptor-positive breast cancer patient may need chemotherapy.
Following a lumpectomy, an estrogen receptor-positive breast cancer patient may need chemotherapy.

The cells in the breast already have receptors to estrogen, which allows them to diversify and show maturity, or breast growth, and create milk ducts. Unfortunately, these cells also replicate in the presence of estrogen and may form bad cell copies that could develop cancer. When cancerous cells actually develop, many of them may retain the normal estrogen receptors. This means they will spread more with regular estrogen exposure. In the premenopausal woman, the female body has near-constant exposure to estrogen and greater risk of these cancers spreading.

An estrogen receptor-positive breast cancer diagnosis may require surgery.
An estrogen receptor-positive breast cancer diagnosis may require surgery.

When breast tissue or lumps are biopsied, it’s now routine to look for the presence of hormone receptors. If these are found, the cancer is considered estrogen receptor-positive breast cancer. A lab report will read positive or negative and may speak to the amount of cells that have these receptors. A high number of estrogen receptor cells suggest that part of successful treatment, given an early stage of the cancer, will be to use hormonal therapy.

Hormonal therapy for estrogen receptor-positive breast cancer should not be confused with hormone replacement therapy (HRT). HRT adds estrogen, risks development of breast cancer and is extremely dangerous in the presence of most breast cancers. Instead, hormonal therapy may use selective estrogen receptor modulators (SERMs) like tamoxifen, which help inhibit the growth signals to the abnormal breast tissue that estrogen excites. There are other medications that may also interrupt this signal or may reduce estrogen production so that tumors grow more slowly or do not recur. The development of these medications, including those that work on progesterone receptor-positive breast cancer, has lead to a pronounced increase in survivability of hormonal-receptor cancers.

Some types of malignancies are not estrogen receptor-positive breast cancer, or, when tested, they contain very few estrogen receptors. Knowing a growth is estrogen receptor-negative is also important to determining treatment. It can then focus on removal of tissue, lumpectomy or mastectomy, and then chemotherapy or radiation to treat cancer cells.

Hormonal receptor-positive cancers involve these treatments too, but are more likely to respond to drugs like SERMs. Medications like tamoxifen may also be used prophylactically when women have strong familial histories of estrogen receptor-positive breast cancer. Clearly women at high familial risk for hormonal breast cancers would also want to avoid extra estrogen or progestin in the form of birth control or HRT.

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