An External Quality Assessment (EQA) program was developed to investigate the status of estrogen receptor (ER), progesterone receptor (PR), and Ki-67 immunohistochemical (IHC) detection in breast cancer and to evaluate the reproducibility of staining and interpretation in 44 pathology laboratories in China. | External quality assessment EQA program for the immunohistochemical detection of ER PR and Ki-67 in breast cancer Results of an interlaboratory reproducibility ring study in China
