Determination of
hormone receptor (estrogen receptor and
progesterone receptor) and
human epidermal growth factor receptor 2 status in the primary
tumor is clinically relevant to define
breast cancer subtypes, clinical outcome,and the choice of
therapy. Retrospective and prospective studies suggest that there is substantial discordance in receptor status between primary and recurrent
breast cancer. Despite this evidence and current recommendations,the acquisition of tissue from metastatic deposits is not routine practice. As a consequence, therapeutic decisions for treatment in the metastatic setting are based on the features of the primary
tumor. Reasons for this attitude include the invasiveness of the procedure and the unreliable outcome of biopsy, in particular for biopsies of lesions at complex visceral sites. Improvements in interventional radiology techniques mean that most metastatic sites are now accessible by minimally invasive methods, including surgery. In our opinion, since biopsies are diagnostic and changes in biological features between the primary and secondary
tumors can occur, the routine biopsy of metastatic disease needs to be performed. In this review, we discuss the rationale for biopsy of suspected
breast cancer metastases, review issues and caveats surrounding discordance of
biomarker status between primary and metastatic
tumors, and provide insights for deciding when to perform biopsy of suspected
metastases and which one (s) to biopsy. We also speculate on the future translational implications for biopsy of suspected metastatic lesions in the context of clinical trials and the establishment of bio-banks of biopsy material taken from metastatic sites. We believe that such bio-banks will be important for exploring mechanisms of
metastasis. In the future,advances in targeted
therapy will depend on the availability of metastatic tissue.