IMMUNOHISTOCHEMISTRY, ESTROGEN RECEPTOR

What this test checks

Measures estrogen receptor (ER) protein in breast cancer tissue. ER-positive breast cancers are fuelled by oestrogen and respond well to hormone-blocking treatments like tamoxifen.

Why do people get this test?

ER status is one of the most important factors in breast cancer treatment planning. ER-positive cancers have more treatment options and generally better outcomes with hormone therapy.

When you should consider this test

• After diagnosis of breast cancer, before planning treatment
• When deciding whether hormone therapy (tamoxifen, aromatase inhibitors) is appropriate
• As part of routine breast cancer receptor panel (ER/PR/HER2)

How to prepare

No preparation needed — performed on biopsy or surgical tissue.