Galleri test shows strong results in large US and Canada trials, marking a potential revolution in early cancer detection
A revolutionary blood test capable of detecting more than 50 types of cancer has shown promising results in large-scale clinical trials across the United States and Canada — potentially changing how cancer is diagnosed and treated worldwide.
The experimental test, known as Galleri, was developed by US-based biotech company Grail. It works by detecting tiny fragments of tumor DNA circulating in the bloodstream, allowing doctors to identify cancer long before symptoms appear.
How the Galleri Test Works
The trial, which followed 25,000 adults over one year, revealed that the Galleri test could accurately detect a wide range of cancers — including several with no current screening programs, such as pancreatic, ovarian, liver, stomach, and bladder cancers.
Among participants who tested positive, 62% were later confirmed to have cancer. In 90% of confirmed cases, the test successfully identified the organ or tissue where the cancer originated. Furthermore, it ruled out cancer correctly in 99% of negative cases, showing strong reliability.
“This could mark a major shift in how we approach early cancer detection,” said Dr. Nima Nabavizadeh, lead researcher from the Oregon Health & Science University, emphasizing the importance of catching cancers early when treatment is most effective.
Promising Early Detection Results
The test was particularly successful in identifying cancers at early stages (Stage I or II) — a crucial factor in improving survival rates. Three-quarters of cancers detected were types not covered by traditional screening programs.
When used alongside current methods for breast, bowel, lung, and cervical cancers, overall detection rates increased sevenfold, suggesting that the test could complement, rather than replace, existing screening tools.
Experts Urge Caution
Despite the enthusiasm, researchers urge caution before wide rollout. Professor Clare Turnbull of The Institute of Cancer Research, London, noted that more randomized controlled trials are needed to confirm whether early detection from this test actually reduces cancer-related deaths.
A much larger UK National Health Service (NHS) trial is currently underway, involving 140,000 volunteers, with results expected in 2026. If proven effective, the test could be offered to up to one million people across the UK.
Mixed Reactions from the Scientific Community
While Sir Harpal Kumar, President of Biopharma at Grail, called the results “very compelling,” others remain cautious.
Naser Turabi of Cancer Research UK warned that overdiagnosis — identifying cancers that might never cause harm — remains a potential risk. “We need strong evidence that early detection through this method truly saves lives,” he said.
The test results are set to be presented at the European Society for Medical Oncology (ESMO) Congress in Berlin, with peer-reviewed publication expected later this year.
