Encouraging data exist demonstrating the potential of cell-free DNA (cfDNA) — also known as liquid biopsy — to help screen patients for several types of cancer. However, this new technology is still in early days and more research will be needed to validate its use, according to a recent review.1

Liquid biopsy is a method that may include analysis of cfDNA in the peripheral blood, or any tumor-derived material, such as DNA, RNA, or intact cells, from bodily fluids. Aside from blood, these fluids can include urine, stool, cerebrospinal fluid, saliva, pleural fluid, and ascites. 

“It is thought the cfDNA is released into the blood stream through apoptosis or necrosis,” the researchers wrote. “More than 40 years ago, it was observed that patients with cancer have higher overall levels of cfDNA than persons without cancer.”

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Research is currently being done to optimize specialized approaches to isolate and analyze cfDNA. If these methods can be optimized, “the ability to analyze tumor-derived DNA from a routine blood draw without the need for an invasive tumor biopsy represents a critical advance with potentially transformative clinical applications,” the authors wrote. 

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One of the potential applications is the use of liquid biopsy for diagnosis and molecular profiling. Research is still underway to determine if the mutational profile established through cfDNA reproduces the profile found from a direct tumor biopsy.

“Early studies, based on small numbers of patient samples, suggested low concordance between DNA alterations detected in tumor and plasma samples from the same patient,” the author wrote. “However, the validity of these studies was compromised by the shortcoming that tumor and plasma samples were often not collected at the same time, yielding potential differences due to molecular evolution of the tumor.”