Abstract
<jats:p>Despite the progress made in treatments and molecular profiling technologies, cancer remains a significant cause of death globally. Treating cancer places a substantial financial strain on public health systems. In the area of both cancer diagnosis and its treatment, tissue biopsy provides insights into the genetic characteristics of a tumour, permitting the estimation of disease progression and the body's reaction to therapeutic regimens. Tissue biopsies have demonstrated that tumours evolve heterogeneity at different stages, due to which a particular therapeutic path becomes problematic in cancer treatment. Obtaining tumour samples through invasive biopsy and conducting molecular analysis has enhanced the ability to plan treatment, assess effectiveness, and track recurrence in cancer patients. Therefore, it is feasible to investigate an alternative method or non-tissue source in early cancer diagnosis and prognosis, like the liquid biopsy technique. Liquid biopsies involve blood analysis, as well as other body fluids like urine or faeces, from cancer patients to detect tumor-specific markers. Liquid biopsy is a preferable type of biopsy compared to older procedures due to its reduced invasiveness, increased sensitivity, and ability to allow repeated samples. This approach enables the consideration of tumour heterogeneity by repeatedly sampling blood or other bodily secretions, as circulating components like circulating tumour DNA, circulating tumour cells, exosomes, or ECV proteins are produced from each cancer clone. This allows for analysis based on time, providing more accurate and up-to-date knowledge of cancer development. Liquid biopsies are currently utilized in various cancer scenarios and serve as the foundation for numerous oncology clinical trials. This chapter presents early diagnostic techniques that focus on several analytes for liquid biopsies. These tests utilize advanced technology and aim to make the initial identification of cancer a routine aspect of preventive medicine, along with healthy living, in the next decade.</jats:p>