A Food and Drug Administration advisory panel narrowly supported the use of a blood-based cancer screening test called Galleri on Wednesday, marking a potential advancement in early cancer detection through less invasive methods. The 10-member Medical Devices Advisory Committee voted 6-4 that the test is effective and 7-2, with one abstention, that its benefits outweigh the risks. All members agreed the test is safe. The FDA is expected to make a final determination in the coming months.
Galleri, developed by the company Grail, analyzes fragments of DNA in blood samples to identify potential signals of more than 50 types of cancer, including stomach, bladder, colorectal, skin, and breast cancer. Although available in the United States since 2021, the test has not yet received formal FDA approval. Grail has proposed use for adults aged 50 and older, emphasizing that Galleri is not intended to replace existing cancer screening methods.
The test costs close to $1,000 and, if approved, could become eligible for coverage by private insurance and Medicaid. Grail has suggested labeling that clarifies the test’s limitations: a negative result does not rule out cancer; a positive result requires further diagnostic testing; the test does not detect all cancers; and the possibility of false positives and false negatives exists.
Advocates highlight Galleri’s potential to detect cancers that currently lack established screening protocols, potentially saving lives through earlier diagnosis. Some committee members expressed cautious optimism, noting the promise of identifying early-stage cancers, which may improve outcomes. Victor van Berkel, division chief of thoracic surgery at the University of Louisville, described his vote in favor as hopeful rather than definitive due to limited data demonstrating clear benefits.
However, critics pointed to a major clinical trial conducted with England’s National Health Service, involving over 140,000 participants, which found that Galleri did not significantly reduce diagnoses of late-stage (stage 3 and 4) cancers. The findings, announced by Grail earlier this year, raise questions about the test’s impact on improving cancer survival rates.
Experts also expressed concerns about the potential harms of false-positive results, which could lead to unnecessary stress and medical procedures, as well as false negatives, which might cause patients to delay or forgo established screening tests. Emil Lou, an oncologist and associate professor at the University of Minnesota, warned against assuming a negative Galleri test is equivalent to an all-clear, stressing the importance of continuing recommended screenings like colonoscopies.
Other specialists, including Scott Ramsey from the Fred Hutchinson Cancer Center and Eric Topol at Scripps Research, urged caution. Ramsey noted that there is no conclusive evidence that Galleri reduces cancer mortality, while Topol pointed to the NHS trial’s failure to demonstrate benefit as a reason for the FDA panel to be circumspect.
Despite the division, the FDA often follows advisory panel recommendations, and a final decision on Galleri’s approval is anticipated later this year. The test represents a broader category of "liquid biopsies," which detect molecular signs of cancer in blood, a rapidly evolving area of cancer diagnostics aiming to broaden early detection beyond current methods.