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Doctors have told health services to prepare for a new era of cancer screening after a study found a simple blood test could spot multiple cancer types in patients before they develop clear symptoms.

The Pathfinder study offered the Galleri blood test to 6,621 adults aged 50 and over and detected dozens of new cases of cancer, 14 were at an early stage and 26 were forms not routinely screened for. The test, which looks for cancer DNA in the blood, was returned for the first time to patients and their doctors to direct cancer research and any necessary treatment.

NHS in the UK describes the test, which is already being used in the US, as a potential “game changer”, raising hope that it will save lives by detecting cancer early enough for treatment to be more effective, but the relevant technology is still being developed. The trial is also due to report results from a major trial involving 165,000 people next year, putting its validity to the test. 

Read more: Tens of thousands in UK on the wait for cancer treatment

Dr. Deb Schrag, a senior researcher on the study at the Memorial Sloan Kettering Cancer Center in New York, told the European Society for Medical Oncology meeting in Paris on Sunday, “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."

Tumors were detected as well through further tests which confirmed blood cancer in 35 people, or 1.4% of the group, and spotted two cancers in a woman who had breast and endometrial tumors.

Besides spotting the presence of disease, the test can pinpoint where the cancer is, permitting doctors to fast-forward the work needed to confirm cancer. “The signal of origin was very helpful in directing the type of work-up, when the blood test was positive, it typically took under three months to get the work-ups completed," Dr. Schrag confirmed. 

She said the test was not yet prepared for screening on a larger scale, specifically population-wide, urging that standard cancer screening must continue while the technology is being advanced. Dr. Schrag also stated that it "still suggests a glimpse of what the future may hold with a really very different approach to cancer screening."

19 solid tumors in tissues such as the breast, liver, lung, and colon, were located by the testing, but it surprisingly spotted ovarian and pancreatic cancers as well, which are usually detected at a later stage, and the remaining were blood tumors. Following in-depth analysis, it was discovered that for 99.1% who were cancer-free, the test was negative, indicating that only a small proportion of healthy people received a false positive result, and approximately 38% of those who had a positive test turned out to have cancer.

Fabrice André, the director of research at Gustave Roussy cancer center in Villejuif, France, said, “Within the next five years, we will need more doctors, surgeons, and nurses, together with more diagnostic and treatment infrastructure, to care for the rising number of people who will be identified by multi-cancer early detection tests.” 

Giving hope for the potential of this scientific breakthrough, 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", adding, “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 long after their cancer is picked up.”

The study's initial findings are expected in 2023. If the trial is successful, the NHS in England wants to expand the rollout to one million more individuals in 2024 and 2025.