FDA Panel Backs Experimental Cancer Blood Test, Citing Potential Benefits

Federal health advisers on Wednesday endorsed a blood test designed to detect signs of various cancers in apparently healthy people, a first-of-its-kind approach that proponents say could revolutionize early cancer detection. However, the panel also cautioned that the technology's effectiveness requires more research.

The Food and Drug Administration's advisory panel voted 7-2, with one abstention, that Grail Inc.'s Galleri test offers more potential benefits than risks, such as false assurances or false alarms. The vote came as the panel raised questions about the technology that still need further investigation.

The Galleri test uses a single blood draw to look for signals of a wide range of tumors. It does not diagnose cancer itself; individuals with a positive result require additional medical evaluation to confirm a cancer diagnosis. The panel affirmed in earlier votes that the test appears safe and effective for use in individuals aged 50 and older.

While companies are actively developing similar blood tests, this endorsement marks the first time a federal advisory group has supported the experimental method. The FDA, which is not bound by the panel's recommendation, is expected to make a final decision in the coming months. If approved, it could significantly increase the availability of such tests, potentially leading to coverage by Medicare and private insurers.

Currently, recommended cancer screenings like mammograms and colonoscopies are designed to detect specific types of tumors. The panel expressed reservations about labeling Grail's test as an "early detection" tool, stating that its effectiveness for this specific purpose has not been definitively shown.

The experts also recommended a list of precautions for doctors and patients. These include: the test should supplement, not replace, existing cancer screenings; a negative result does not guarantee the absence of cancer; and further studies are necessary to prove the test's benefit compared to established screenings.

Grail's test is already available to consumers in the U.S. for over $700 out-of-pocket. FDA approval could broaden access by making it eligible for insurance coverage.

During discussions, FDA staff and outside experts highlighted potential downsides. The test has been shown to miss a significant number of real cancers and can produce false positives in healthy individuals. Its accuracy in detecting early-stage cancers, when treatment is often more effective, was also a point of concern. Grail did not provide data demonstrating that screening with its test led to reduced cancer deaths, a metric that would require long-term follow-up studies.

Grail representatives argued that the test is a significant advancement because it can detect more than 50 types of cancer, including many for which no screening options currently exist, such as liver and ovarian cancer. "Patients want opportunity, they want options," said Dr. Mylyna Massart of the University of Pittsburgh, who presented on behalf of Grail. "They want the chance to fight their disease while the chance to survive is possible."

A primary study involving 140,000 older adults showed Grail's test detected about one-third of cancers diagnosed over a one-year period. Approximately two-thirds of patients who received a "cancer signal detected" result were later confirmed to have cancer.

However, FDA reviewers reinterpreted the company's data to emphasize potential risks. The agency's chief reviewer noted that the test missed two out of every three cancers diagnosed in the subsequent year, potentially providing false reassurance to many patients.

Consumer advocates also voiced concerns that individuals might delay seeking medical attention for early cancer symptoms if they received a negative result from the DNA test. "When they start having symptoms there will be tendency to delay going to the doctor — just a little bit — and that could be deadly," said Diana Zuckerman of the nonprofit National Center for Health Research during a public comment period. "They will be told to continue other screening, but will they?"