Progesterone receptor negative. Breast cancer cells that do not have a protein (receptor molecule) to which progesterone will attach. Breast cancer cells that are PR- do not need the hormone progesterone to grow and usually do not respond to hormonal therapy.
PR
Meaning of PR in English
NCI English Dictionary of Cancer Terms. Английский словарь раковых терминов NCI(Национальный институт злокачественных новообразований). 2012