WS8-1 - Current landscape and future perspectives of biomarker study in breast cancer

Abstract

Breast cancer (BC) is a heterogeneous disease encompassing multiple tumor subtypes with distinct morphology, behavior and clinical implications. Biomarkers play an essential role in the management of women with BC. The appropriate use of molecular biomarkers enables us for patients with BC to receive optimal treatment. Established biomarkers, such as estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER-2), and Ki-67, play significant roles in BC to predict the prognosis and decide the specific therapy to each patient. According to current guidelines, the additional biopsy from tumor tissues at metastatic sites is recommended for the analysis of current status of the diseases. However, difficulties in obtaining tumor tissues at metastatic sites frequently hinders clinicians to perform biopsies from metastatic tumors, and clinicians often depends on the phenotype of the primary tumor for the treatment decisions in metastatic breast cancer. In addition, serial tissue biopsy sampling is essential for the evaluation of current disease status but, this cannot be easily accomplished, are sometimes inaccessible or may not fully reflect tumor heterogeneity. Recently, liquid biopsy enables us to analyze several circulating biomarkers such as circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) in the blood of patients and could give us useful information on the current disease status. Assessing tumor biology in real time by CTCs or ctDNA may serve to detect minimal residual disease, discover therapeutic targets, and predict response to treatment. In this paper, I will cover the potential role of biomarkers on overcoming tumor heterogeneity, on their potential relevance for tumor surveillance and monitoring, and for the selection of therapeutic options.