Fact Check

What We Know About the Cancer-Detecting Blood Test

The “revolutionary” large-scale trial is a world first.

Published Sep 13, 2021

Image Via Grail
In mid-September 2021, the National Health Service in England announced the world’s first trial for a new cancer-detecting blood test.

In September 2021, British health officials announced the launch of the world’s largest trial of a blood test capable of detecting more than 50 types of cancer before symptoms appear.

Headed by The Cancer Research UK, the National Health Service (NHS) in England, and King’s College London, the so-named Galleri trial aims to recruit 140,000 volunteers across eight areas of England. Galleri checks for the earliest signs of cancer. If it's successful, its ability to catch cancer during its earliest stages could be a “game-changer” in the fight against the disease.

“This quick and simple blood test could mark the beginning of a revolution in cancer detection and treatment here and around the world,” said NHS Chief Executive Amanda Pritchard in a news release. “By finding cancer before signs and symptoms even appear, we have the best chance of treating it and we can give people the best possible chance of survival.”

While its early cancer detection ability holds promise, Galleri does not diagnose cancer and does not detect all forms of the disease. Blood drawn from a participant is tested for chemical changes in fragments of the blood’s genetic code known as cell-free DNA (cfDNA), which leaks from tumors into the bloodstream. Previous research conducted by Galleri founding company Grail showed that the test was effective at finding cancers that are difficult to identify early on, like head and neck, bowel, lung, pancreatic, and throat cancers.

As of this writing, Galleri is not approved by the U.S. Food and Drug Administration (FDA) but was granted a breakthrough device designation in 2019 under a government-led voluntary program for certain medical devices "that provide for more effective treatment or diagnosis of life-threatening or irreversibly debilitating diseases or conditions." The test joins two other similar tumor-testing tests that were approved in the U.S., according to the consumer publication Evaluate. Galleri is available in the U.S. for $949, and is available for prescription only. Because it is new to the market and does not have FDA approval, the test is not covered by health insurance.

Galleri is designed to detect more than 50 types of cancer. Grail

Galleri doesn’t rule out cancer, but instead helps providers to evaluate and confirm whether and where cancer may exist. It is intended to be used in coordination with other screening practices and is not a replacement but rather a method to inform the next steps of diagnosis.

For the British trial, tens of thousands of recruitments between the ages of 50 and 77 — those most at risk for cancer — will be asked to give blood samples at mobile testing clinics across the country. Regardless of their results, the test is designed to detect cancer signals such as cfDNA and predict where in the body those signals exist. Half of the participants in the randomized control trial will have blood samples screened with the test right away, while the other half will have their sample stored and tested in the future. This will allow researchers to compare the stage at which cancer is detected between the two groups. Regardless, study participants will be notified if their test signals potential cancer.

Early cancer detection during stage one or two allows for more treatment options, some of which can be less aggressive and harmful. Patients whose cancer is identified at the earliest stage may see up to ten times the survival rate compared to a person who learned of cancer at stage four.

Those who give blood as part of the British trial will be invited to participate in later stages of the trial one and two years later. Initial results are expected by 2021 and if successful, researchers plan to extend the rollout to 1 million people by 2025.


“GRAIL Announces Significant Progress with Multi-Cancer Early Detection Test Including FDA Breakthrough Device Designation.” GRAIL, https://grail.com/press-releases/grail-announces-significant-progress-with-multi-cancer-early-detection-test-including-fda-breakthrough-device-designation/. Accessed 13 Sept. 2021.

“Grail Launches Pan-Cancer Screen – for Those Who Can Pay out of Pocket.” Evaluate.Com, 4 June 2021, https://www.evaluate.com/vantage/articles/news/snippets/grail-launches-pan-cancer-screen-those-who-can-pay-out-pocket.

Health, Center for Devices and Radiological. “Breakthrough Devices Program.” FDA, Jan. 2021. www.fda.gov, https://www.fda.gov/medical-devices/how-study-and-market-your-device/breakthrough-devices-program.

King’s Leads the World’s Largest Trial of Cancer Blood Test. https://www.kcl.ac.uk/news/kings-leads-the-worlds-largest-trial-of-cancer-blood-test. Accessed 13 Sept. 2021.

NHS England » NHS Launches World First Trial for New Cancer Test. https://www.england.nhs.uk/2021/09/nhs-launches-world-first-trial-for-new-cancer-test/. Accessed 13 Sept. 2021.

https://www.england.nhs.uk/2021/09/nhs-launches-world-first-trial-for-new-cancer-test/. Accessed 13 Sept. 2021.

“Our Products.” GRAIL, https://grail.com/our-products/. Accessed 13 Sept. 2021.

Madison Dapcevich is a freelance contributor for Snopes.