Vol. 7, Issue 2, Part B (2025)

Cancer treatment has significantly advanced with the emergence of targeted therapies and immunotherapy, yet minimal residual disease (MRD) continues to pose a major challenge. MRD, characterized by a small number of residual cancer cells post-treatment, increases relapse risk and complicates patient management. Traditional MRD detection methods, such as invasive tissue biopsies and bone marrow aspirates, are effective but come with patient discomfort and procedural risks. Liquid biopsy has revolutionized MRD monitoring by providing a non-invasive alternative that analyzes biomarkers in body fluids, such as blood. This approach includes the evaluation of circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and extracellular vesicles (EVs), offering real-time, dynamic insights into disease status. Recent advancements in liquid biopsy technologies have markedly improved sensitivity and specificity for MRD detection. ctDNA, which reflects tumor genetic alterations, has demonstrated high sensitivity for detecting residual disease and predicting relapse across various cancers, including leukemia, colorectal cancer, and breast cancer. CTCs, which provide insights into tumor dissemination, have shown promise in monitoring disease progression and response to treatment. EVs, containing molecular signatures of the tumor, offer additional non-invasive monitoring capabilities. Despite its potential, liquid biopsy faces challenges related to standardization, cost, and technology limitations. Ensuring consistent methodologies, reducing costs, and improving accessibility are critical for broader implementation. Future research focuses on enhancing sequencing technologies, refining CTC isolation methods, and exploring additional biomarkers, such as epigenetic markers. Integrating liquid biopsy with traditional diagnostic tools may offer a more comprehensive approach to MRD monitoring, ultimately advancing precision oncology and improving patient outcomes.