Novel strategies in liquid biopsy

Cancer, a leading global cause of death, involves complex processes and multiple components. Due to the lack of effective and accurate early diagnostic methods, many patients are diagnosed with advanced cancer. Traditional tissue biopsy, while common, may increase the risk of metastasis. In contrast, liquid biopsy technology utilizes bodily fluids such as blood, urine, and saliva to analyze tumor-associated information, including circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), exosomes, and various molecular markers. This technology has undergone rapid advancements, enabling its routine clinical use in cancer patients and broadening research horizons. ctDNA and CTCs can be isolated and analyzed from blood sample, providing valuable insights for therapeutic choices. However, technical and clinical challenges remain, such as the low proportion of ctDNA in circulating free DNA, the short half-life of ctDNA in blood, and the low concentration and heterogeneity of CTCs. Exosomes, abundant and stable vesicles released by most cells, carry bioactive molecules and play a pivotal role in intercellular communication, tumorigenesis, and progression. They offer advantages over CTCs and ctDNA but also present challenges in isolation, detection, and specificity. This review summarizes recent technologies for detecting ctDNA, CTCs, and exosomes in liquid biopsies, including nanotechnology, sensor technology, spectroscopy, microfluidic technology, and aptamers. It highlights their clinical applications and future development directions, elucidating their promising prospects in diagnosing cancer patients, monitoring disease progression, and predicting prognosis.