A Breakthrough in Early Cancer Detection
The North American trial monitored 25,000 adults from the United States and Canada over a period of one year. Each participant provided a blood sample that was analyzed for traces of cancerous DNA fragments, known as cell-free DNA, that circulate in the bloodstream when tumors begin to form.
Of all participants, around one in 100 received a positive result from the Galleri test. Among those, 62% were later confirmed to have cancer, marking a major breakthrough in the potential accuracy of blood-based cancer diagnostics.
Lead researcher Dr. Nima Nabavizadeh, associate professor of radiation medicine at Oregon Health & Science University, said the results highlight a fundamental shift in how doctors might approach cancer screening.
“This test could fundamentally change our approach to cancer detection,” Dr. Nabavizadeh explained. “It allows us to find many types of cancer earlier—when treatment success rates and even cures are far more likely.”
High Accuracy and Wide Coverage
One of the most promising aspects of the study is the test’s accuracy. The Galleri test correctly ruled out cancer in over 99% of participants who tested negative, greatly reducing the risk of false positives.
Even more impressively, when used alongside existing cancer screening programs—such as those for breast, bowel, and cervical cancers—the test increased the total number of cancers detected by seven times.
Most notably, about 75% of the cancers detected were those that currently have no national screening program, including ovarian, liver, stomach, bladder, and pancreatic cancers—all of which are notoriously difficult to diagnose early.
In nine out of ten confirmed cases, the blood test was also able to accurately identify the cancer’s point of origin, allowing for faster and more targeted treatment plans.
A Step Toward Transforming Cancer Care
These results suggest that Galleri could soon become a crucial tool in global cancer prevention strategies. By identifying the disease before symptoms appear, healthcare systems could dramatically improve survival rates and reduce the need for aggressive late-stage treatments.
However, experts caution that more research is still needed to fully understand the long-term benefits.
Professor Clare Turnbull, an expert in translational cancer genetics at the Institute of Cancer Research, London, said the findings were encouraging but emphasized the importance of further testing.
“We need data from randomized studies that measure whether earlier detection through Galleri actually reduces cancer mortality,” she explained. “Only then can we determine the real impact of this technology.”
Awaiting Peer Review and NHS Trial Results
While the headline results of the North American study will be presented at the European Society for Medical Oncology (ESMO) congress in Berlin, the full data have yet to be published in a peer-reviewed journal.
The next key milestone will be the release of results from a major three-year NHS trial involving 140,000 patients in England, expected in 2026.
The UK’s National Health Service (NHS) has been running this large-scale pilot since 2021 to evaluate the effectiveness of the Galleri test in real-world settings. If the findings are positive, the NHS has said it plans to extend testing to over one million people across the country.
Global Experts Call Results ‘Compelling’
Sir Harpal Kumar, President of Biopharma at Grail, described the latest results as “very compelling,” emphasizing how early detection could revolutionize cancer care worldwide.
“The vast majority of people who die from cancer do so because we find their cancers too late,” he told BBC Radio 4’s Today programme. “The goal is to shift toward earlier detection when treatments are more effective and often curative.”
Currently, many cancers—such as pancreatic or ovarian—are discovered only in advanced stages, when treatment options are limited. Galleri’s ability to catch these earlier could mark a major turning point in oncology.
Balancing Hope with Caution
While excitement around the technology is growing, some experts urge caution until long-term evidence confirms its effectiveness and safety.
Naser Turabi from Cancer Research UK welcomed the findings but noted that researchers must ensure the test does not lead to overdiagnosis—the detection of cancers that might never have caused harm during a person’s lifetime.
“Further research is essential to make sure we don’t overdiagnose cancers that may not have caused problems,” Turabi said. “The UK National Screening Committee will play a key role in evaluating the evidence before the test is rolled out more widely.”
A Glimpse Into the Future of Cancer Screening
If successful, the Galleri test could mark one of the most important advancements in medical history. With its ability to detect multiple types of cancer through a single blood draw, it promises a simpler, faster, and more comprehensive way to screen millions of people each year.
By catching cancer early—often before symptoms even begin—this test could help turn one of humanity’s deadliest diseases into a far more treatable condition.
The world now watches closely as the results of the NHS trial approach. Should the evidence continue to support Galleri’s potential, the test could soon be offered globally, changing the landscape of cancer detection forever.