From the Guidelines
A liquid biopsy is a minimally invasive medical test that examines a sample of blood or other bodily fluids to detect cancer cells or pieces of DNA from tumor cells circulating in the fluid. Unlike traditional tissue biopsies which require surgical removal of tissue, liquid biopsies are minimally invasive procedures requiring only a simple blood draw. These tests can detect circulating tumor cells (CTCs), cell-free DNA (cfDNA), exosomes, and other biomarkers released by tumors into the bloodstream. Liquid biopsies are particularly valuable for monitoring treatment response, detecting disease recurrence, identifying potential drug targets, and tracking tumor evolution over time. They're especially useful when traditional biopsies are difficult to perform due to tumor location or patient health concerns. The scientific principle behind liquid biopsies is that tumors shed cellular material into bodily fluids, providing a "snapshot" of the cancer's genetic makeup. While liquid biopsies offer numerous advantages including reduced patient discomfort and the ability to perform repeated testing, they may not completely replace traditional biopsies in all situations due to sensitivity limitations with very early-stage cancers.
Some key points to consider about liquid biopsies include:
- They can be used to detect various types of cancer, including lung, breast, and colon cancer 1
- They can be used to monitor treatment response and detect disease recurrence 1
- They can be used to identify potential drug targets and track tumor evolution over time 1
- They are minimally invasive and can be performed repeatedly with minimal patient discomfort 1
- They may not be as sensitive as traditional biopsies for detecting very early-stage cancers 1
Overall, liquid biopsies are a valuable tool in the diagnosis and management of cancer, and can provide important information about the genetic makeup of a tumor. However, they should be used in conjunction with other diagnostic tests and clinical evaluations to ensure accurate diagnosis and effective treatment.
From the Research
Definition of Liquid Biopsy
- A liquid biopsy is a non-invasive diagnostic tool that analyzes circulating nucleic acid (cfDNA and cfRNA), circulating tumor cells (CTCs), extracellular vesicles (EVs), and tumor-educated platelets (TEPs) in blood or other body fluids to provide valuable insights into tumor biology 2.
- It involves the analysis of circulating extracellular nucleic acids (cell-free DNA; cfDNA), circulating tumor DNA (ctDNA), and circulating tumor cells (CTCs) isolated from the blood and other body fluids 3.
Components of Liquid Biopsy
- Circulating tumor DNA (ctDNA) is single- or double-stranded DNA released by tumor cells into the blood, harboring the mutations of the original tumor 4.
- Circulating tumor cells (CTCs) can be isolated using biomarker-based cell capture, and positive or negative enrichment based on biophysical and other properties 3.
- Extracellular vesicles (EVs) and tumor-educated platelets (TEPs) are also analyzed in liquid biopsies to provide a comprehensive view of tumor characteristics 2.
Clinical Applications of Liquid Biopsy
- Liquid biopsies are used for cancer molecular profiling, enabling a precision oncology approach 3.
- They can be used to predict response and resistance to targeted therapy and chemotherapy, as well as immunotherapy, including CAR-T cells 3.
- Liquid biopsies can also assess shed DNA from multiple metastatic sites, potentially actionable alterations, and prognosis and tumor burden 3.
- They have the potential to revolutionize cancer care by providing rapid, non-invasive, and cost-effective diagnostics, enabling timely interventions and personalized treatment strategies 2.
Challenges and Limitations
- Liquid biopsy faces several challenges, particularly in detecting analytes in early-stage cancers and evaluating the tumor molecular fraction 2.
- Tumor burden, molecular fraction, and the presence of subclones can impact the sensitivity and specificity of the analysis 2.
- Recent advancements in artificial intelligence (AI) have enhanced the diagnostic accuracy of liquid biopsy by integrating data, and multimodal approaches show promise in providing a more comprehensive view of tumor characteristics 2.