Breast cancer markers
ER negative
Also written as ER-, Oestrogen receptor negative, Estrogen receptor negative
What it means
ER negative means the cancer cells do not have a protein that binds to oestrogen (estrogen). They do not need oestrogen to grow, and they do not stop growing when treated with substances that block oestrogen.
Why it matters
Hormone-blocking medicines are not expected to work on ER negative cells. Your oncologist plans other options.
Ask your oncologist
"If my cancer is ER negative, which treatments are we considering instead?"
From NCI Dictionary of Cancer Terms: estrogen receptor negative. Not medical advice: your oncologist decides.