Journal of Clinical & Experimental Pathology
Open Access

Liquid biopsy is a new, non-invasive diagnostic procedure that can detect molecular biomarkers in body fluids like blood, urine, and cerebrospinal fluid, particularly in an area of cancer. This procedure differs from standard tissue biopsy, which involves surgical or needle extraction of tissue samples, which may cause considerable risks and discomfort to patients. Liquid biopsy has transformed clinical diagnostics by providing a less invasive, readily repeatable alternative that can provide real-time information about illnesses' molecular and genetic state. Parts of DNA are released by tumor cells during apoptosis or necrosis. circulating tumor DNA (ctDNA) contains tumor-specific genetic mutations and epigenetic alterations, providing a non-invasive space into the cancer's genetic profile. Liquid biopsy showed possibilities for diagnosing cancer in its early stages, even before clinical signs appear. Many malignancies require early identification to improve prognosis and survival rates. The capacity of liquid biopsy to detect ctDNA or Circulating Tumor Cells (CTCs) allows the detection of cancer-specific genetic abnormalities, such as point mutations, copy number variations, and DNA methylation modifications, all of which are characteristic of early carcinogenesis.

One of the primary advantages of liquid biopsy is its ability to screen asymptomatic individuals. For example, in liquid biopsy methods, such as CancerSEEK, are being developed to detect many cancers using a simple blood test that analyzes ctDNA and protein biomarkers. These tests are designed to detect cancer at an early stage, allowing for timely intervention and lowering cancer-related mortality. Traditional biopsies provide an indication of the tumor's genetic makeup at a given period of time. Tumors, on the other hand, are dynamic entities that evolve over time and frequently acquire resistance to treatments. This ability to monitor dynamically provides essential information into treatment efficacy and informs therapeutic modifications to prevent or overcome resistance. In patients with Non- Small Cell Lung Cancer (NSCLC) treated with targeted therapy, liquid biopsy is utilized to detect changes in the Estimated Glomerular Filtration Rate (EGFR) gene, such as the T790M resistance mutation. When this mutation is detected, physicians may proceed to second- or third-generation Tyrosine Kinase Inhibitors (TKIs), which are particularly intended to overcome resistance, improving patient outcomes. Minimal Residual Disease (MRD) is defined as a small number of cancer cells that may remain in the body after therapy but are undetectable by standard imaging or tissue biopsy. MRD is a strong predictor of recurrent cancers and its diagnosis is important for making future treatment decisions. Liquid biopsy enables highly sensitive detection of ctDNA, revealing early signs of MRD and identifying individuals at risk of relapse.

In clinical practice, liquid biopsy is used to track MRD in diseases like leukemia, colorectal cancer, and breast cancer. Researchers have indicated that the identification of ctDNA after surgery or chemotherapy is associated with an increased risk of recurrence, allowing clinicians to commence adjuvant medicines or enhance treatment regimens to prevent relapse. Liquid biopsy is important in personalized medicine because it allows for the genetic characterization of cancers without requiring invasive tissue sampling. Genetic profiling of ctDNA in cancers such as melanoma, breast cancer, colorectal cancer, and prostate cancer can reveal actionable mutations that can be targeted with specific therapies, such as Poly- ADP Ribose Polymerase (PARP) inhibitors for BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) mutations or immune checkpoint inhibitors for tumors with high mutational burdens. This method to personalizing therapy based on the tumor's genetic landscape results in more effective and less toxic treatments, which improves patient outcomes.

Liquid biopsy enables researchers to non-invasively capture the diversity of tumor cells and their genetic alterations, providing a more complete picture of tumor evolution than a single tissue biopsy. By studying ctDNA and CTCs, researchers can investigate the clonal dynamics of tumor cells in response to treatment, giving information on resistance mechanisms and discovering novel therapeutic targets. For example, liquid biopsy has been used to monitor the appearance of Kristen Rat Sarcoma viral oncogene homolog (KRAS) mutations in colorectal cancer patients treated with EGFR inhibitors, indicating that resistant cells might spread under treatment pressure. Liquid biopsy is an effective method for identifying new indicators for cancer detection, prognosis, and therapy response. Liquid biopsy is increasingly being used as a diagnostic tool in clinical studies to classify patients and track therapy response. Researchers employ liquid biopsies in experimental settings to test the efficacy and pharmacodynamics of new drugs, as well as to find resistance mechanisms. By testing ctDNA, researchers may evaluate the reduction in tumor-specific mutations in response to treatment, providing early evidence of therapeutic efficacy.

Liquid biopsy represents an important development in clinical and experimental pathology by providing a non-invasive, dynamic, and complete approach to disease diagnosis and monitoring. Its ability to collect real-time data on tumor genetic features provides significant potential for developing personalized therapy, improving patient outcomes, and developing experimental research discoveries. While challenges that get remain, the future of liquid biopsy appears positive, with ongoing developments set to make it an essential component of modern pathology.