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Cancer DNA in blood | Blog | County Pathology Ltd

Cancer DNA in blood


Two new studies on patients with breast and prostate cancers add to growing evidence that detecting bits of cancer DNA circulating in the blood can guide patient treatment.
Dr. Nick Turner of Britain's Institute of Cancer Research said the technology had huge potential but more evidence was still needed. "What is really missing at the moment is the hard evidence that using liquid biopsy and treating patients on that basis improves hard endpoints like how long the patient lives. The field really needs those studies to change practice," he said.

Still, small steps are being taken. In January, for example, Qiagen NV launched a liquid biopsy in lung cancer as a companion diagnostic for drugs that target epidermal growth factor receptor in cases when a tissue sample is not available. And the scientific evidence is building.

In a study on Wednesday in the journal Science Translational Medicine, researchers using liquid biopsies in 97 men with prostate cancer found genetic mutations that may be driving drug resistance in those who fail to respond to conventional therapy.

The work by scientists at Italy's University of Trento suggests liquid biopsies could be used to guide treatment. A second study in the journal Nature Communications tracked a single woman with metastatic breast cancer over three years and, by comparing tissue and liquid biopsies, found that blood tests accurately reflected genetic changes in her tumors over time.

Dr. Keith Stewart, an oncologist who heads Mayo Clinic's Center for Individualized Medicine, believes liquid biopsies are the future, but it may take three to five years to fully understand how useful they will be. "I'm very confident liquid biopsies will become a routine part of clinical practice in cancer," he said.

What is missing is data showing that early intervention based on liquid biopsies actually affects outcomes - but there are more and more hints. Dr. David Hyman of Memorial Sloan Kettering Cancer Center in New York is presenting results this weekend from a study showing that patients whose tumor DNA in the blood fell by 50% or more 21 days into therapy fared much better than others.

Hyman agrees more testing should be done, looking at how consistently the tests perform and how much they help patients. "The only way to do that is to bring these technologies forward and to test them in the clinic, often in the context of pivotal clinical trials, to demonstrate that these technologies have value. I think we're on the cusp of doing that," he said.