The importance of biopsy in clinically diagnosed metastatic lesions in patients with breast cancer.

Background: Receptor status discordance, such as estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status between primary breast cancer and metastatic lesions has been reported. The aim of this study was to evaluate the biopsy of clinically diagnosed metastatic lesions and to determine the changes in hormonal receptor and HER2 status of the metastatic lesions.

Methods: Sixty-three patients with clinically diagnosed metastatic breast cancer underwent an excisional biopsy or core needle aspiration guided by computed tomography/ultrasound. ER, PR and HER2 were assessed by immunohistochemistry (IHC).

Results: A total of 48 metastases (76.2%) and nine second primary malignancies (14.3%, seven primary lung cancers and two primary pancreatic cancers) were found. The discrepancies between ER, PR and HER2 status between the primary breast cancer and metastatic lesions were 14.6%, 16.7% and 8.3%, respectively. Six lesions (9.5%) were proved benign upon biopsy.

Conclusions: The biopsy of clinically suspicious metastatic lesions could histologically confirm the diagnosis of metastasis, evaluate discrepancies between ER, PR and HER2 status and exclude secondary malignancy, which might change the therapeutic strategy for breast cancer patients.