Abstract:

BACKGROUND: Discordance in biomarker expression between primary and metastatic tumor sites has been reported in several studies; yet, few have examined this feature in bone lesions.
METHODS: We retrospectively enrolled patients with breast cancer metastasis to the bone or bone marrow, excluding cases where samples from both the primary and metastatic lesions were not available. Expression patterns of the estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2) and Ki67 were compared in primary tumors and bone or bone marrow lesions.
RESULTS: Forty-six patients with a median age of 52 years (range, 34-72 years) were included in the study. Discordant rates of ER, PgR and HER2 were 20%, 46% and 0%, respectively. Physicians usually determined treatment options considering the results of biomarker re-evaluation. It is unlikely that biomarker discordance was related to prior treatment.
CONCLUSIONS: Biomarker discordance in bone or bone marrow lesions is common in patients with breast cancer. An accurate and thorough analysis of biomarkers and metastatic tumor properties is important for clinical decision-making.

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