A new blood test detects multiple cancers without clear symptoms, study finds

Doctors are hailing a new era in cancer screening after a study found a simple blood test could detect multiple cancer types in patients even before they display clear symptoms. According to a press release from the biotechnology company GRAIL, the Pathfinder study evaluated multicancer early detection (MCED) screening using a blood test and the clinical care pathways on more than 6000 individuals aged 50 or older—an age group at elevated risk for cancer—and detected dozens of new cases of the disease.

"The PATHFINDER study is an exciting first step towards fundamental change in the approach to cancer screening. The study found cancer in about 1% of participants including types for which there is no established screening method. The study demonstrated the feasibility of this paradigm and solid test performance," said Deb Schrag, MD, MPH, chair, Department of Medicine at Memorial Sloan Kettering Cancer Center in New York. "Although continued public health efforts to optimize adherence to existing screening strategies that have been proven effective are critical, this study provides a glimpse of what the future may hold—the opportunity for screening using blood tests to detect various types of cancers at their earliest and most treatable stages."

It is the first time that Galleri test results—which screen for cancer DNA in the blood—have been sent to patients and clinicians to help guide cancer investigations and any necessary treatment, reports The Guardian. Of the 6,621 adults aged 50 and older who were offered the Galleri blood test, a cancer signal was reportedly detected in 92 participants. Further examinations revealed that 35 patients, or 1.4% of the research group, had solid tumors or blood cancer. Speaking at the European Society for Medical Oncology meeting in Paris on Sunday, Schrag said: "I think what’s exciting about this new paradigm and concept is that many of these were cancers for which we do not have any standard screening."

Beyond detecting the presence of disease, the test predicts where the cancer will be found, helping doctors to expedite the follow-up work required to discover and confirm a cancer. "The signal of origin was very helpful in directing the type of work-up," said Schrag. "When the blood test was positive, it typically took under three months to get the work-ups completed." Although she cautioned that the test was not yet ready for population-wide screening and that people must continue with standard cancer screening while the technology is improved, she added: "But this still suggests a glimpse of what the future may hold with a really very different approach to cancer screening."

Naser Turabi, the director of evidence and implementation at Cancer Research UK, said, "Blood tests for multiple types of cancer used to belong in the realm of science fiction, but now they are an area of cancer research that is showing promise for patients. Research like this is crucial for making progress against late-stage cancers and giving more patients the chance of a good outcome. The Pathfinder trial results give us a better understanding of how frequently cancer is found by this blood test in people who haven't been previously diagnosed. But we will need data from larger studies to fully assess this test and other similar tests in development, especially to understand whether people actually survive for longer after their cancer is picked up."