The cfDNA released from tumor cells is referred to as circulating tumor DNA (ctDNA). ctDNA has the potential to be a marker of tumor response to treatment. Conversely, an increase in ctDNA could precede radiographic progression by weeks or months, studies have shown. 

Any full integration of cfDNA into clinical use will require “careful understanding of the advantages and limitations of this approach for proper interpretation of results to guide clinical decision making.”

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The authors stressed that further prospective study of the use of cfDNA is needed, adding, though, that it has the “potential to have a transformative effect on cancer medicine.”

Some of the examples they discussed included a recent study by Chan and colleagues that used Epstein-Barr virus (EBV) DNA in plasma to look for nasopharyngeal carcinoma in more than 20,000 Chinese patients.2 Using this method, they found that 1.5% of patients (309 individuals) had detectable EBV in their DNA and 0.17% of the entire population (34 of the 309) had nasopharyngeal carcinoma upon endoscopic evaluation. Only 1 patient who was negative for EBV in plasma DNA had nasopharyngeal carcinoma within a year following screening. 

Disclosure: The authors of the original study report various fees from pharmaceutical and molecular testing companies. For a full list of disclosures, please refer to the original study.


  1. Corcoran RB, Chabner BA. Application of cell-free DNA analysis to cancer treatment  [published October 31, 2018]. N Engl J Med.doi: 10.1056/NEJMra1706174
  2. Chan KCA, Woo JKS, King A, et al. Analysis of plasma Epstein–Barr virus DNA to screen for nasopharyngeal cancerN Engl J Med. 2017;377:513-522.