What should you know about ER immunohistochemistry?

ER stands for oestrogen receptor. In immunohistochemistry, a pathologist applies antibodies to a tissue sample; a visible stain indicates receptor protein in the tested cells. The report may describe whether staining is absent or present and how extensive or strong it is.

The result is one part of tumour assessment. It is interpreted with the biopsy findings, tumour grade, stage, progesterone receptor and HER2 results, and your overall circumstances. An ER-positive result can support discussion of hormone-based treatment; it does not by itself determine every treatment decision.

Ask for a copy of the pathology report and ask what the ER wording means in your case. Confirm which sample was tested and whether the laboratory had enough representative tissue. If the result is unexpected or borderline, your specialist may discuss review or additional testing.

Bring the report to the appointment where treatment is planned. The team may combine it with imaging, lymph-node information and other tumour tests before recommending surgery, radiotherapy, hormone treatment, chemotherapy or targeted treatment.

The test itself does not usually create urgent symptoms. Seek prompt advice for a biopsy site with increasing redness, swelling, drainage, bleeding or fever, and contact your cancer team quickly if new symptoms develop while treatment is being arranged.

Is my tumour ER-positive or ER-negative? How was the result measured? Does it change my treatment options? Should another sample or pathology review be considered?