A new study has brought hopeful news about a blood test called Galleri, which is designed to detect more than 50 types of cancer—often before symptoms appear.
The test works by looking for tiny bits of DNA that cancer cells release into the bloodstream. These bits of DNA act like a fingerprint, revealing signs of cancer early.
The Galleri test is currently being studied in the U.K. and U.S., and it can be given as a yearly screening. A large U.S. study called Pathfinder 2 just revealed that the test correctly identified cancer in about 62% of people who had a positive result. In other words, if Galleri found a cancer signal, there was a 61.6% chance that the person actually had cancer.
Even more promising, in 92% of cases where the test detected cancer, it could also tell doctors which organ or tissue the cancer came from. This helps doctors save time and avoid unnecessary tests and scans. The test also proved to be highly reliable at ruling out cancer in healthy people, with a 99.6% accuracy rate in people who did not have the disease.
The study involved more than 23,000 people from the U.S. and Canada who had no cancer symptoms. They were followed for at least a year.
The results showed that Galleri found more than seven times as many cancers as traditional screening programs like those for breast or bowel cancer. Out of 216 people with a positive Galleri test, 133 were diagnosed with cancer.
Importantly, the test was able to detect cancer in its early stages. Over half of the cancers it found were at stage I or II, and nearly 70% were found at stages I to III. Early-stage detection is key to successful treatment and better outcomes.
The test could also be especially helpful for cancers that do not currently have regular screening options, such as pancreatic, liver, head and neck, and ovarian cancers. For patients with vague symptoms like abdominal pain, Galleri can guide doctors to the right tests more quickly, making diagnosis more efficient.
Experts say the test might be most useful for people aged 50 and older, as this is when cancer risk rises sharply. However, people who are younger but have risk factors—like a personal or family history of cancer—might also benefit.
Despite the promising results, some experts are cautious. Professor Anna Schuh from Oxford noted that 40% of people who received a positive result did not actually have cancer, meaning the test gave false positives almost half the time. This could lead to unnecessary stress and additional tests.
Also, while the test works well for some common cancers with a 74% detection rate, it performs less well for rarer types, with only 40% accuracy. These concerns may affect how useful and cost-effective the test would be for public health systems like the NHS.
Other scientists, including Professor Clare Turnbull and Professor Nitzan Rosenfeld, said more data is needed—especially on whether the test can help lower cancer death rates. Still, many agree that the test shows great promise. It could help detect many cancers that currently go unnoticed until later stages.
In conclusion, the Galleri test could become an important tool in cancer care. It might help doctors catch cancer earlier, guide treatments, and improve outcomes for many patients. But it’s not perfect yet, and more research is needed to understand how best to use it in everyday healthcare.
If you care about cancer, please read studies that a low-carb diet could increase overall cancer risk, and vitamin D supplements could strongly reduce cancer death.
For more information about health, please see recent studies about how drinking milk affects the risks of heart disease and cancer and results showing higher intake of dairy foods linked to higher prostate cancer risk.
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