FDA Panel Reviews First Multi-Cancer Blood Test

How the Galleri Test Works

Galleri is a prescription-only blood test that analyzes cell-free DNA (cfDNA) circulating in the bloodstream. The test looks for cancer-associated methylation patterns that can distinguish signals associated with cancer from normal biological activity.

When Galleri detects a cancer signal, it also attempts to predict the Cancer Signal Origin (CSO) — the organ or tissue where the cancer may have originated.

That information is intended to help physicians determine which additional diagnostic tests may be appropriate. A positive Galleri result does not itself establish a cancer diagnosis. Patients would still require diagnostic evaluation, such as imaging, laboratory testing, endoscopy or biopsy, depending on the suspected cancer.

The proposed FDA indication is for adults 50 years of age and older. Importantly, a "No Cancer Signal Detected" result would not mean that a person is cancer-free. FDA materials emphasize that people should continue recommended screening for individual cancers, such as breast, colorectal, cervical and lung cancer when applicable.

Evidence From Large Clinical Studies

The FDA's review includes evidence from two major prospective studies.

The NHS-Galleri trial in England enrolled approximately 142,826 participants aged 50 to 77. It was a randomized controlled study conducted through the UK's National Health Service.

Participants were assigned either to a group offered Galleri screening in addition to standard cancer screening or to a control group receiving standard screening. The study was designed to examine whether adding multi-cancer screening could ultimately shift cancer diagnoses toward earlier stages.

The second major study is PATHFINDER 2, a large U.S.-based prospective interventional study involving approximately 25,000 participants in the data submitted for FDA review.

Together, these studies provide a large evidence base for evaluating how the test performs in a screening population.

GRAIL says its broader clinical development program includes more than 385,000 participants across multiple studies, although the FDA's PMA review focuses on specific prespecified datasets and analyses.

The Central Question: Does Earlier Detection Improve Outcomes?

The most important issue before the FDA panel is not simply whether Galleri can detect cancer.

The more difficult question is whether detecting cancer earlier through a blood test ultimately improves health outcomes for patients.

This distinction is critical in cancer screening. Detecting additional cancers does not automatically demonstrate that screening saves lives. Some cancers may grow slowly and might never become clinically significant, while other aggressive cancers may still be difficult to detect early.

The NHS-Galleri study therefore provides both encouraging findings and important limitations.

The trial did not meet its primary endpoint of reducing the combined incidence of Stage III and Stage IV cancers among the prespecified cancer types.

It also did not demonstrate a reduction in overall cancer mortality during the period evaluated.

However, additional analyses have produced findings that GRAIL argues are important. The company has reported evidence of increased detection of earlier-stage cancers and a reduction in certain Stage IV diagnoses, particularly after multiple screening rounds.

The distinction matters because Stage IV cancer generally indicates metastatic disease, while cancers diagnosed at earlier stages may be more amenable to curative treatment.

FDA reviewers and advisory committee members therefore face a complex question: How much weight should be given to evidence of stage shifting when a direct mortality benefit has not yet been demonstrated?

Sensitivity and False Positives

Another major issue is the test's diagnostic performance.

No cancer screening test detects every cancer. Galleri's performance varies considerably depending on cancer type and stage.

FDA materials describe the test using measures such as episode sensitivity, positive predictive value (PPV), negative predictive value (NPV) and specificity.

In the studies submitted for review, Galleri demonstrated relatively high specificity and positive predictive value, while its sensitivity was lower than 100% and varied among different cancers.

This creates an important trade-off.

A test designed to screen millions of apparently healthy people must minimize false-positive results. Otherwise, patients could undergo unnecessary imaging, invasive procedures and other diagnostic tests.

At the same time, a test that misses too many cancers could provide false reassurance.

For that reason, the FDA panel is examining not only how many cancers Galleri detects, but also what happens to patients after receiving both positive and negative results.

Potential Benefits for Cancers Without Routine Screening

One of the strongest arguments for multi-cancer detection technology is the large number of cancers for which there is currently no routine population-wide screening test.

Existing screening programs focus on specific cancers where evidence has demonstrated that screening can reduce disease burden or mortality.

However, many other cancers — including pancreatic, ovarian, liver and several other cancers — do not currently have comparable routine screening programs for the general population.

Galleri is designed to search for molecular signals from many cancer types simultaneously.

This could potentially change the way physicians approach cancer screening by moving some cancers from a symptom-driven diagnostic model toward a screening-based model.

At the same time, the absence of an established screening program for a particular cancer does not automatically mean that detecting it earlier will improve mortality. Demonstrating that clinical benefit remains one of the central challenges for the technology.

What Happens After a Positive Result?

A multi-cancer test could also change the workload of the healthcare system.

If a patient receives a Cancer Signal Detected result, the next step is a diagnostic investigation to determine whether cancer is actually present and, if so, where it originated.

This can involve consultations, imaging studies, laboratory tests and potentially invasive procedures. Coordinating this comprehensive workup directly involves primary care clinicians and specialized Physicians / MD-DO across medical oncology, gastroenterology, and diagnostic radiology.

As a result, widespread adoption could increase demand for:

• Diagnostic imaging
• Oncology consultations
• Pathology services
• Biopsies and other procedures
• Primary care follow-up
• Cancer treatment services
• Genetic and molecular testing
• Care coordination

In outpatient clinics and ambulatory health systems, multidisciplinary intake teams led by experienced Nurse Practitioners (NP) play a pivotal role in ordering targeted secondary imaging, interpreting CSO reports, and counseling patients through the diagnostic odyssey.

The healthcare system would therefore need sufficient capacity to manage additional diagnostic work generated by screening.

The Financial Question

Cost is another major consideration.

The current list price for Galleri is approximately $949, although the actual amount paid by a patient may vary depending on the provider, employer or other arrangements.

The test is currently not routinely covered by Medicare or most health insurance plans.

FDA approval could change the economic environment substantially.

Congress has authorized Medicare coverage for FDA-approved multi-cancer detection tests under specified conditions. As a result, regulatory approval could potentially create a much larger reimbursable market for Galleri and future competing tests.

The economic consequences could extend beyond GRAIL itself.

A successful regulatory pathway could encourage additional companies to invest in competing blood-based cancer detection technologies, potentially increasing competition in the emerging MCED market.

Implications for Healthcare Providers

If Galleri eventually receives FDA approval, physicians could face new questions about how the test should fit into routine preventive care.

Primary care providers, for example, may need to determine which patients are appropriate candidates, explain the limitations of the test and manage follow-up after positive or negative results.

Healthcare organizations could also need new protocols for handling Cancer Signal Detected results.

This raises broader questions about clinical guidelines, physician training, diagnostic capacity and communication with patients.

To support acute biopsy and endoscopy suites, healthcare facilities are increasingly turning to specialized Registered Nurses (RN) / Travel Nursing professionals to staff interventional radiology rooms, manage procedural recovery, and coordinate patient navigation protocols.

Furthermore, to ensure equitable access and rapid follow-up across geographic regions, many health networks are expanding remote oncology navigation services staffed through Telehealth / Remote / Virtual Jobs, enabling timely pre-test shared decision-making and rapid virtual review of screening results.

The test would not replace established screening programs. Instead, the proposed use is as an additional screening tool alongside existing guideline-recommended cancer screening.

A Potential New Market for Cancer Screening

The regulatory review could also have implications for the rapidly developing multi-cancer early detection industry.

A number of biotechnology and diagnostic companies are developing blood-based technologies designed to detect cancer-associated molecular signals.

FDA approval of the first major MCED test could provide a regulatory precedent for the entire sector.

It could also influence how future companies design clinical trials. Regulators, insurers and healthcare providers may increasingly demand evidence not only that a test detects cancer, but that its use leads to meaningful improvements in patient outcomes.

That could shift the industry's focus from laboratory performance toward long-term clinical evidence.

FDA Advisory Vote Is Not the Final Decision

Today's advisory committee vote will not itself approve or reject Galleri.

The committee provides expert advice and recommendations to the FDA. The agency will make the final regulatory determination after considering the committee's recommendations, the submitted evidence and other regulatory factors.

The FDA's review therefore represents an important step, but the ultimate decision remains with the agency.

What the Decision Could Mean

The Galleri review represents a broader debate about the future of cancer screening.

The potential advantage is straightforward: a single blood test could potentially identify signals from many different cancers, including cancers that currently lack routine screening options.

The challenge is equally important: healthcare regulators must determine whether finding those cancers earlier produces enough clinical benefit to justify the costs, follow-up procedures and potential harms associated with false-positive and false-negative results.

The FDA's decision could therefore have consequences extending well beyond one diagnostic product.

If Galleri is approved, it could accelerate the adoption of multi-cancer screening, molecular diagnostics and blood-based preventive medicine while potentially opening a substantial new Medicare and commercial insurance market.

If additional evidence is required before approval, it could reinforce the importance of demonstrating long-term outcomes — particularly reductions in advanced disease and cancer mortality — before MCED tests become part of routine population screening.

Either way, the September 23 advisory committee meeting marks an important point in the development of a new category of cancer diagnostics and could help establish how regulators, physicians and insurers evaluate multi-cancer detection technologies in the years ahead.