Chuck Bednar for redOrbit.com – @BednarChuck
A new blood test capable of detecting cancer DNA in a patient could allow oncologists to make sure that a treatment is and continues to be effective, without the need for a traditional biopsy or a CT scan, according to new research published in the journal The Lancet Oncology.
The technique, known as a liquid biopsy, would allow doctors to find evidence of cancer DNA in a patient’s bloodstream, and quickly allow them to abandon find alternatives to failing treatments (potentially reducing harmful side effects), the New York Times reported on Sunday.
“This could change forever the way we follow up not only response to treatments but also the emergence of resistance, and down the line could even be used for really early diagnosis,” Dr. José Baselga, physician in chief and chief medical officer at Memorial Sloan Kettering Cancer Center who was not involved in the research, told the newspaper.
Studies have shown the technique can be successful
In the study, researchers from the National Cancer Institute and their colleagues used the method on 126 patients suffering from diffuse large-B-cell lymphoma, and found that the test was able to correctly predict recurrences three-to-five months earlier than possible using a CT scan. Also, the study found that liquid biopsies could identify patients unlikely to respond to treatments.
Similarly, the Los Angeles Times reported on another study, presented by an international team of scientists at the American Association for Cancer Research meeting in Philadelphia this week, found that the liquid biopsy blood test provided doctors with a non-invasive way to determine if some types of lung cancer would respond to treatment with the drug crizotinib.
The method used a simple to see if non-small cell lung cancer would respond to the medication, and the study authors analyzed blood samples from 77 patients with well known mutations. They were able to identify nearly two-thirds of the patients that had what is known as an EML4-ALK fusion gene rearrangement, and their findings appear to support the theory that in some cases, the liquid biopsy method is as effective at detecting cancer biomarkers as traditional biopsies.
Searching for the “bar codes” of cancer DNA
Dr. Levi Garraway of the Dana-Farber Cancer Institute told the New York Times that his lab does not currently use the technique, but said that it was “exciting,” that he and his colleagues were “very interested” in it and that it was “a top priority.”
Sloan Kettering oncologist Dr. David Hyman added that “every cancer has a mutation” that can be tracked using the technique, which he said was “like bar coding the cancer in the blood.” The concept for the test, the newspaper explained, was born out of the discovery that fetuses give off little pieces of DNA into the bloodstreams of their mothers.
As it turned out, all growing cells (even tumor cells) shed these genetic fragments, the Times said, but it is not easy to find them. Attempt to detect them only became truly effective when researchers turned to advanced DNA sequencing techniques and found hundreds of mutations that could act like bar codes for cancer, then developed the technology to find them.
Currently, liquid biopsies allow tumors to be monitored more frequently than is possible with traditional biopsies, and it could potentially be used to find and treat cancer earlier, or to help doctors determine which types of cancer patients require which types of treatments (i.e., which Stage 2 colon cancer patients require chemotherapy along with surgery).
A recent Australian stud showed that only six to eight percent of cancer patients whose blood did not have detectable cancer DNA suffered a recurrence of tumors, the New York Times noted. A new study involving some of those scientists are now investigating further with a random trial of 450 patients, with those who the blood test find have cancer DNA receiving chemotherapy while those who do not receive the liquid biopsy will receive regularly prescribed care.
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