Changes in estrogen receptor, progesterone receptor and Her-2/neu status with time: discordance rates between primary and metastatic breast cancer.

BACKGROUND: Changes in the receptor profile between primary and metastatic breast cancer tissue have been suggested. The degree of hormone receptor discordance in archival paired pathological samples was evaluated. MATERIALS AND METHODS: Archival data were collected on 100 patients for whom tissue from primary and metastatic sites was available. Estrogen receptor (ER), progesterone receptor (PR) and Her-2/neu status in the primary and metastasis were compared. RESULTS: The discordance rate for ER was 17.7% (2-sided p=0.0039) with 9.7% of tumours changing from ER-positive to ER-negative and 8.0% changing from ER-negative to ER-positive. The discordance rate for PR was 37.3% (2-sided p<0.0001), with all of these tumours changing from PR-positive to PR-negative. No significant discordance for Her-2/neu was found. CONCLUSIONS: This series suggests that significant discordance exists for hormone receptor status between primary and metastatic breast cancer samples. Loss of PR was particularly frequent.