[Clinical outcome of receptor expression discordance between primary and metastatic breast cancer]

Objective: To investigate the clinical outcome of expression discordance of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER-2) in primary breast cancer and the corresponding metastatic lesions. Methods: A retrospective analysis was performed on 178 breast cancer patients with metastasis confirmed by the National Cancer Center & Cancer Hospital, Chinese Academy of Medical Sciences in the past 6 years. The data of expressions of ER, PR and HER-2 in primary and metastatic breast cancer, the metastatic sites, disease progression were collected and the relationships of the expression discordance of receptors with prognosis were analyzed. Results: The discordance rates of ER, PR and HER-2 between the primary tumor and the metastatic sites were 27.0%, 39.8% and 18.7%, respectively. The discordance rates of ER, PR and HER-2 of patients with locoregional recurrence were 21.9%, 36.6% and 12.7%, respectively, while those of patients with distant metastases were 31.3%, 42.7% and 23.8%. The median progression free survivals (PFS) of ER+/+、ER+/-、ER-/+、ER-/- of primary tumor and metastatic sites were 17.7 months, 10.3 months, 14.0 months and 9.0months, respectively (P=0.025). The median PFS of PR+/+, PR+/-, PR-/+, PR-/- were 23.0 months, 10.7 months, 14.0 months and 9.2months, respectively (P=0.002). The median PFS of HER-2+/+, HER-2+/-, HER-2-/+, HER-2-/- were 14.9 months, 15.2 months, 12.3 months and 14.0 months, respectively, without significant differences (P=0.588). Conclusions: This study confirms that expression discordances of ER, PR and HER-2 between primary breast cancer and the corresponding metastatic lesions are dramatic, especially in the patients with distant metastasis. The unstable levels of ER and PR seem to be significantly associated with prognosis of breast patients.