Breast cancer biomarker discordance between primary and sites of metastasis: A systematic review.

e11574 Background: Systemic treatment choices for breast cancer patients with recurrent disease are usually based on the ER/PR/Her2 biomarker status of the primary cancer. Biomarker discordance between the primary and metastatic sites is well recognised and could have important therapeutic implications. A systematic review was conducted to assess the extent of biomarker discordance between the primary cancer and metastasis, and whether is influenced by the site of metastasis. Methods: An electronic search of multiple literature databases implemented by an information scientist was conducted to identify studies reporting outcomes of ER/PR/Her2 receptor stability between primary site and recurrent disease. Seven reviewers independently screened the 5034 abstracts and full text articles, which were identified according to pre-defined selection criteria. The same reviewers performed data collection from all included studies. Studies that were identified reported on receptor conversion between primary sites of...