FDA Advisers Back Blood Test That Screens for a Dozen Cancers at Once

An advisory panel of outside experts convened by the Food and Drug Administration voted Wednesday that a blood test designed to flag signs of more than a dozen cancers in people with no symptoms does more good than harm, moving the product a step closer to becoming the first test of its kind sold in the United States with full federal approval.

The Molecular and Clinical Genetics Panel, meeting at the agency's White Oak campus in Silver Spring, Maryland, voted 7 to 2, with one abstention, that the benefits of the Galleri test outweigh its risks for the population GRAIL Inc. wants to screen: adults 50 and older with no clinical suspicion of cancer. The panel was unanimous, 10 to 0, that the test is safe, but split narrowly, 6 to 4, on whether there is enough evidence that it actually works as intended.

What the vote means

Galleri has been sold since 2021 as a laboratory-developed test, a category the FDA has historically not required to go through formal premarket review. GRAIL is now seeking full approval through the agency's premarket approval pathway, the most rigorous form of device clearance, which would let doctors order it as a regulated medical test rather than a wellness product and could open the door to Medicare and private insurance coverage that has so far been largely absent.

The test works by drawing a single tube of blood and analyzing chemical tags, known as methylation patterns, on fragments of DNA that tumors shed into the bloodstream. A machine-learning algorithm looks for patterns associated with cancer and, when it finds one, predicts which organ the signal likely came from to help doctors decide where to look next. The company says the test screens for signals associated with more than 50 cancer types, though the pivotal data presented to the panel focused on 12 cancers, including lung, pancreatic, ovarian, stomach and esophageal cancer, that together account for roughly two-thirds of U.S. cancer deaths.

The numbers behind the vote

The panel's review centered on interim results from PATHFINDER 2, the largest U.S. interventional study of a multi-cancer test to date, which enrolled nearly 36,000 adults. In the group analyzed, the test's sensitivity, meaning how often it correctly flagged an actual cancer, ran to roughly 40 percent across all cancer types and rose to nearly 70 percent for the dozen deadliest cancers it targets. Specificity was about 99.6 percent, meaning false alarms were rare, and a little under two in three positive results were later confirmed to be real cancer, according to figures GRAIL and researchers presented, as reported by Oregon Health & Science University, a trial site.

Those figures sit alongside more sobering results from a separate, government-run trial in Britain. The NHS-Galleri trial, which screened more than 140,000 people ages 50 to 77, missed its main goal of shifting cancer diagnoses to earlier, more treatable stages when stage III and stage IV cancers were counted together. It did find a 14 percent reduction in stage IV diagnoses and a 19 percent increase in cancers caught at stages I through III, but the mixed result has fueled debate among screening researchers about how much benefit the test delivers in practice.

Who would be affected

Galleri is aimed squarely at older adults already following standard screening advice, not as a substitute for mammograms, colonoscopies or lung cancer scans but as an add-on meant to catch cancers, such as pancreatic or ovarian tumors, for which no routine screening test exists. According to data GRAIL presented, layering Galleri on top of the four cancer screenings the U.S. Preventive Services Task Force currently recommends for average-risk adults, for breast, cervical, colorectal and lung cancer, more than quadrupled the number of cancers detected within a year compared with those four screenings alone.

Cost remains a barrier. The test currently runs about $949 out of pocket when purchased directly through GRAIL, and most insurers, including traditional Medicare, do not cover it. Full FDA approval would not force insurers to pay for the test, but device industry analysts and patient groups have said it would make coverage decisions far more likely, since insurers are generally reluctant to pay for products lacking formal agency clearance.

What people are saying

Panel members who voted in favor stressed that older adults deserve the option to look for cancers that currently go undetected until they are advanced, even if the evidence is imperfect. Panelists who voted against the effectiveness question, or abstained on the overall benefit-risk vote, said the data left too many open questions, including how often the test misses early-stage cancers, when treatment tends to work best, and whether a negative result might lull patients into skipping screenings they still need.

"We don't have the evidence in front of us today to say this test can detect those types of cancers," said Charity Morgan, a biostatistics professor at the University of Alabama at Birmingham who sat on the panel, according to BioPharma Dive's account of the meeting.

Deborah Armstrong, an oncology professor at Johns Hopkins University who also sat on the panel, said the risk of patients skipping guideline-recommended screenings after a reassuring Galleri result could be managed as long as patients understood what the test could and could not tell them. GRAIL's chief executive framed the vote as validation of the company's approach. "The Galleri test was developed to improve the effectiveness and efficiency of our national cancer screening program by adding multi-cancer early detection to recommended screening," said Josh Ofman in a statement GRAIL released following the vote, adding that the goal is "helping find more cancers safely, when they may be easier and less costly to treat."

What happens next

The FDA is not required to follow its advisory panels' recommendations, though it typically gives them significant weight in reaching a final decision, which the agency has said is expected within the coming months. If approved, Galleri would become the first multi-cancer early detection test to carry full FDA marketing authorization in the United States, a milestone that could accelerate development of rival tests already in earlier stages of study, including two other assays the National Cancer Institute has selected for its own Vanguard Study on multi-cancer screening.

Even with approval, public health researchers cautioned that years of additional follow-up data will be needed to determine whether catching cancers earlier through the test actually translates into people living longer, a question that neither PATHFINDER 2 nor the NHS-Galleri trial has fully answered. Until then, doctors are likely to keep describing Galleri as a supplement to, not a replacement for, the screenings already recommended for adults at average risk.