Estrogen receptor positive. Breast cancer cells that have a protein (receptor molecule) to which estrogen will attach. Breast cancer cells that are ER+ need the hormone estrogen to grow and will usually respond to hormone (antiestrogen) therapy that blocks these receptor sites.
ER+
Meaning of ER+ in English
NCI English Dictionary of Cancer Terms. Английский словарь раковых терминов NCI(Национальный институт злокачественных новообразований). 2012