Current and Developing Liquid Biopsy Techniques for Breast Cancer

Simple Summary Breast cancer is the most common cancer and leading cause of death worldwide. Therefore, it is important to diagnose and treat breast cancer early. Current diagnostic methods include mammography and tissue biopsy; however, they have limitations. Liquid biopsy is a less invasive tool for diagnosis. In this review, we summarize and focus on the recent discoveries on liquid biopsy and development of detection techniques. Breast cancer is the most commonly diagnosed cancer and leading cause of cancer mortality among woman worldwide. The techniques of diagnosis, prognosis, and therapy monitoring of breast cancer are critical. Current diagnostic techniques are mammography and tissue biopsy; however, they have limitations. With the development of novel techniques, such as personalized medicine and genetic profiling, liquid biopsy is emerging as the less invasive tool for diagnosing and monitoring breast cancer. Liquid biopsy is performed by sampling biofluids and extracting tumor components, such as circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), cell-free mRNA (cfRNA) and microRNA (miRNA), proteins, and extracellular vehicles (EVs). In this review, we summarize and focus on the recent discoveries of tumor components and biomarkers applied in liquid biopsy and novel development of detection techniques, such as surface-enhanced Raman spectroscopy (SERS) and microfluidic devices.