For years, the idea seemed as far-fetched as a fairy tale.
Once upon a time, there was a tumor cell that died. Its innards spilled out into the bloodstream of the body where it had lived. The owner of that body went to a doctor and got a blood draw for a test, which identified the cell’s floating DNA fragments as cancer. The doctor then drew up a personalized treatment plan based on those bits of DNA, and the patient lived happily ever after …
The appeal of a simple blood test to detect and analyze cancer is obvious. It could replace the necessary evil of tissue biopsies — invasive, often risky and painful procedures to collect tumor cells with a needle or through surgery. A vial of blood sounds like a better trade than a chunk of tissue.
Recently, the idea of these so-called “liquid biopsies” seems less like a fantasy. The U.S. Food and Drug Administration approved its first liquid biopsy test in 2016. It could detect mutations in a single gene in lung cancer patients.
Genetic sequencing technology has evolved rapidly since then. Today at the American Association of Cancer Research annual meeting, researchers presented results from a clinical trial that found a commercial blood test was as effective as tissue biopsies at detecting multiple genetic mutations in lung cancer patients. All of the mutations have targeted drugs available for them, meaning the liquid biopsy could help guide treatment.
Those results are incredibly exciting, said several experts at Fred Hutchinson Cancer Research Center. But they caution that a fairy-tale ending for liquid biopsies hasn’t been written just yet. Their verdict: Don’t expect blood tests to replace the oncologist’s needle anytime soon.
“This latest trial shows that liquid biopsies are a reality,” said Dr. Nancy Davidson, senior vice president and director of the Clinical Research Division at Fred Hutch and president and executive director of its clinical-care partner, Seattle Cancer Care Alliance. “But the question is, how big of a reality can they be?”
