What is a Liquid Biopsy Test?

A liquid biopsy targets and identifies pieces of DNA from tumor cells that are circulating within the blood. This enables researchers to detect mutations in DNA, which could potentially identify various types of cancers in the early stages including lung cancer, prostate cancer, ovarian cancer, gastrointestinal cancer, colorectal cancer, and breast cancer. It is minimally invasive and therefore, multiple liquid biopsy tests can easily be collected over time if needed.

How Does Liquid Biopsy Work?

A liquid biopsy involves the following two primary stages:

1. A blood sample is taken from the individual.
2. The blood sample is analyzed with Next-Generation Sequencing (NGS) technology for any Circulating tumor cells or cancer cells (for research use only).

With NGS, a large number of mutations in many genes from a significant number of samples can be detected. By using targeted NGS panels, where specific lists of curated gene targets are chosen for particular sample applications, sequencing can be focused on clinically relevant targets so that each target is sequenced thousands or tens of thousands of times to ensure a high degree of sensitivity.

How Accurate is a Liquid Biopsy?

High specificity is achieved using error-correction techniques with NGS. This removes errors that arise from the sequencing and amplification of the DNA.

Advantages of Liquid Biopsy

Liquid biopsy offers the following advantages:

• Early detection of cancers and therefore early diagnosis
• Minimally invasive, only requiring a blood test (whereas tissue biopsies might require surgery)
• Creating customized treatment plans
• Identifying when treatments are effective or ineffective
• Detecting any remaining cancer or relapse
• Rapid results from NGS

What are the Challenges of Liquid Biopsy?

As the methodology is still in active development, two key challenges are important to consider when choosing a liquid biopsy workflow. As with many developing technologies, validation of liquid biopsy results by alternative tests or technologies may still be needed to ensure accuracy of results for certain research or clinical applications until the proper level of validations has been performed. Second, because there is a low fraction of cell-free DNA (cfDNA) samples, the accuracy of detecting a rare mutation can be challenging.