estrogen receptor positive
Meaning of estrogen receptor positive: A result that reads like a label but works as a prediction, since it forecasts which treatments a tumor is likely to answer.
Definition of estrogen receptor positive
Estrogen receptor positive describes cancer cells that carry the receptor protein for estrogen, shown by staining a sample of the tumor. Cells with that receptor can be driven to grow by the hormone, which makes them vulnerable to treatments that block estrogen or lower its supply. The status is written ER positive and is reported for nearly every breast cancer.
How is the status decided?
A slice of the tumor is treated with an antibody that sticks to the estrogen receptor and carries a stain, so the nuclei of cells holding the receptor turn dark under the microscope. A pathologist records the proportion of cells that stain and how strongly. Above an agreed threshold the tumor is reported positive, below it negative. A narrow band just above the cutoff is reported as low positive, because tumors there behave more like estrogen receptor negative ones than the plain label suggests.
Why does it change treatment?
Because a receptor that drives growth is also a handle to grab. Two strategies follow from a positive result: block the receptor so estrogen cannot reach it, which is what a selective estrogen receptor modulator does, or cut off the hormone supply so little estrogen is available to bind. Which is chosen depends largely on whether the ovaries are still producing hormone. Neither approach helps a tumor without the receptor, so the test decides eligibility rather than merely describing.
What is reported alongside it?
| Marker | What a positive result implies |
|---|---|
| Estrogen receptor | Hormone-blocking treatment is likely to work |
| Progesterone receptor | Supports the estrogen result and refines the outlook |
| HER2 | Points to antibody treatment aimed at that protein |
The three are read together, and the combination sorts breast cancers into groups that behave differently. A tumor negative for all three is called triple negative.
Does the status ever change?
It can. A deposit appearing long after the original tumor does not always match it, so the estrogen receptor is often measured again on new tissue rather than assumed from the first report. Losing the receptor is one route by which a cancer stops responding to hormone treatment.
Also known as
Used in a sentence
The tumor was reported as estrogen receptor positive and HER2 negative.
Good to know
Receptor status describes the tissue actually tested, and a recurrence can differ from the original tumor, which is why the receptor is often measured again on new material when disease returns.
Word origin
Where “estrogen receptor positive” comes from
Estrogen joins the Greek oistros, meaning frenzy or gadfly, with the ending -gen, meaning producing; receptor comes from the Latin recipere, to receive.