Receptor discordance among primary tumors, brain metastases and extra-brain metastases in patients with breast cancer

To investigate the expression status of estrogen receptor (ER), progesterone receptor (PR) and HER2 in patients with breast cancer brain metastases (BM). Patients who underwent craniotomy for BM were included. The status of ER, PR and HER2 (including HER2-low expression) in primary breast tumors (PT), BM and extra-BM (EM) was determined. Between PT and BM, conversion of hormone receptor and HER2 occurred in 28% (30/107) and 12% (10/86) of cases. When considering three-tiered categorization of HER2, the conversion rate reached 31%. In the paired EM and BM (n = 39), the discordance rates were 18, 3 and 22%, respectively. Receptor discordance was dynamic and relevant, especially using new HER2 categorization.