LIQUID BIOPSY IN BREAST CANCER: A PARADIGM SHIFT IN BIOMARKER MONITORING

Resumo

Breast cancer (BC) is one of the leading causes of cancer mortality among women worldwide. Tissue biopsy is considered the gold standard for diagnosis; however, it is an invasive procedure and limited in representing tumor heterogeneity. In this sense, liq uid biopsy (LB) emerges as a minimally invasive tool for early and personalized detection. Given the above, this study aims to analyze the role of liquid biopsy in detecting tumor biomarkers and its application in the diagnosis, therapeutic monitoring, and prognosis of breast cancer. A narrative review was conducted using the PubMed database. The search strategy utilized the descriptors: “liquid biopsy” AND “breast cancer.” Randomized clinical trials, controlled studies, and systematic reviews published between 2021 and 2026 in English were included. Among the main liquid biopsy biomarkers, circulating tumor DNA (ctDNA) stands out. It consists of DNA fragments released by tumor cells, allowing for the identification of clinically relevant mutations and the detection of minimal residual disease (MRD). Circulating tumor cells (CTCs), in turn, are intact neoplastic cells associated with prognosis and tumor dissemination. Furthermore, extracellular vesicles, especially exosomes, reflect the tumor's molecular profile and participate in intercellular communication, acting both as biomarkers and in disease progression. It is concluded that liquid biopsy represents a promising tool in precision oncology, contributing to a more dynamic and individualized approach to th e management of breast cancer.