Abstract
Various tumor cells may exhibit different genetic or phenotypic characteristics. This phenomenon of cancer cells, known as Tumor Heterogeneity, is responsible for multiple cancer sites caused in a single patient through metastases. It is possible that the biopsy of the most accessible metastasis will not provide enough information to reexamine tumor features and make therapeutic recommendations. Liquid biopsy is a diagnostic technique that probes metastatic deposits from biofluids like peripheral blood for cell-free DNA (cfDNA)/circulating tumor DNA (ctDNA) from cancer patients. This analysis provides researchers and oncologists a comprehensive insight into therapeutic targets and treatment resistance-causing gene alterations. Various studies have validated that cfDNA/ctDNA may be essential in tumor analysis, constituting the need for the identification of cancer cells that may reactivate and proliferate, causing the disease to reoccur. This detection is also called Minimal Residual Disease (MRD) and shares insights on the efficiency of the treatment regimen and if the cancer cells have developed resistance to a specific treatment regimen. In this review, the significance of cfDNA/ctDNA as a possible diagnostic, prognostic, or monitoring biomarker for solid tumors has been evaluated in recent studies, and its clinical relevance in routine cancer clinics in India has been reviewed.