Galleri: a multi-cancer blood test, with its strengths and blind spots

How Galleri Multi-Cancer Early Detection Test works

Tumors release small pieces of DNA into the bloodstream. Galleri sequences this cell-free DNA and looks for methylation patterns, chemical tags on DNA that differ between cancer and normal tissue. If a cancer signal is found, the test also predicts the likely tissue or organ of origin to guide further testing.

Who it’s for, and who it isn’t

What’s included

• Clinician discussion of whether Galleri fits your age, risk and screening history
• Clinician order and blood draw
• Results reviewed with a licensed clinician
• If a signal is detected, guidance on next steps and referral for diagnostic work-up
• No membership fee

Possible side effects

• Brief sting and possible bruising from the blood draw
• False-positive results can lead to scans, biopsies and anxiety
• False-negative results can give false reassurance
• Follow-up procedures after a positive result carry their own risks

This isn’t a complete list. Your clinician reviews risks, interactions and warnings with you before prescribing. In an emergency, call 911.

What the evidence says

In FDA materials for a September 2026 advisory panel, 12-month sensitivity was 35.0% in the U.S. PATHFINDER 2 study and 31.6% in the NHS-Galleri trial, with specificity above 99.7% and positive predictive values of 77.0% and 66.2%. Sensitivity was low for breast and prostate cancer and for stage I to II cancers. The NHS-Galleri trial did not meet its primary goal of reducing stage III and IV cancers, and a reduction in cancer deaths has not been shown.

What Galleri looks for

Most cancer screening checks one organ at a time: a mammogram for breast, a colonoscopy for colon. Galleri takes a different approach. It analyzes DNA fragments circulating in your blood and looks for methylation patterns that tend to appear in cancer.

When it finds a signal, the report predicts where the cancer probably started. In FDA's review documents, that prediction was correct in more than 9 out of 10 true-positive cases, which helps doctors decide which scans or tests to do next.

How accurate it is

The most up-to-date figures come from the FDA executive summary for the September 23, 2026 advisory panel, which drew on two large studies:

• Sensitivity (cancers found among people diagnosed with cancer within 12 months): 35.0% in PATHFINDER 2 and 31.6% in NHS-Galleri
• Specificity (people without cancer correctly told no signal): 99.85% and 99.74%
• Positive predictive value (positive results that turned out to be cancer): 77.0% and 66.2%
• Detection of stage I to II cancers: about 25% and 21%
• Prostate cancer sensitivity about 11%; breast cancer roughly 19% to 26%

What those numbers mean for you

Galleri rarely raises a false alarm, which is its main strength. But it misses roughly two out of three cancers present, and it is weakest for early-stage cancers and for common cancers that already have good screening tests, such as breast and prostate.

So a negative result is not an all-clear. It should never lead you to skip a mammogram, colonoscopy or other recommended screening. And a positive result is not a diagnosis; roughly a quarter to a third of positives in these studies did not turn out to be cancer within a year.

Does it save lives?

That has not been shown. In the NHS-Galleri randomized trial in England, adding Galleri did not significantly reduce the combined rate of stage III and IV cancers, which was the trial's main goal. The company reported fewer stage IV diagnoses in later screening rounds for a group of aggressive cancers and more early-stage cancers found, but finding more cancers is not the same as preventing deaths.

Experts at the FDA panel debated exactly this gap between detection and proven benefit.

Who might reasonably consider it

Age is the biggest driver of cancer risk, which is why the studies and the FDA application focus on adults 50 and older. Galleri may be worth discussing if you are in that group, are already current on recommended screenings, and want to add a test that can pick up some cancers with no routine screening option, such as pancreatic or ovarian cancer.

It is a less obvious fit if you are younger with no special risk, if you are behind on standard screening, or if you would struggle with the uncertainty of a false positive. Your clinician will help you weigh these points before ordering.

Where FDA review stands

Galleri is currently offered as a laboratory-developed test performed in GRAIL's own lab; it has not been approved by the FDA. GRAIL submitted a premarket approval application in January 2026 for screening adults 50 and older.

On September 23, 2026, the FDA's Molecular and Clinical Genetics Panel voted unanimously on safety, 6 to 4 that the test is effective, and 7 to 2 with one abstention that its benefits outweigh its risks. The panel's advice is not binding, and as of October 2026 the FDA has not announced a decision.

If a cancer signal is detected

Your clinician will go through the result with you promptly and help arrange diagnostic testing, usually imaging and sometimes procedures, guided by the predicted origin. In PATHFINDER 2, most people with a signal had at least one invasive procedure as part of that work-up, so it is worth thinking ahead about how you would handle the process.

If tests do not find cancer, your clinician will discuss what follow-up, if any, makes sense.

Price and insurance

Galleri is $1,095, one-time, confirmed during your eligibility review. Insurance generally does not cover it, and HealifyMD does not bill insurance. There is no membership fee.