Early detection is one of the most effective tools in improving cancer outcomes. Traditional screening methods such as mammography, colonoscopy and low-dose CT have saved countless lives, but they only target specific cancer types. The emerging field of multi-cancer early detection (MCED) testing offers a new possibility: identifying multiple cancers with a single blood test.
Nebraska Medicine oncologist Kelsey Klute, MD, explains how the Galleri® multi-cancer early detection test works, where it fits into early screening and when providers should consider offering it to patients.
How the Galleri test works
“The Galleri test looks for tumor DNA circulating in the peripheral blood,” says Dr. Klute. “Everyone has free DNA fragments in their blood that come from normal cell turnover, but this test can distinguish between normal cell-free DNA and tumor DNA.”
The test uses methylation patterns, or chemical modifications that influence gene expression, to identify cancer-associated DNA and predict where the cancer signal might be coming from.
“We all have the same DNA in every cell, but methylation patterns vary depending on the tissue type,” Dr. Klute says. “By analyzing those patterns, the test can suggest a likely tissue or organ of origin if a cancer signal is detected.”
Results typically return within a couple of weeks and are reported as either “cancer signal detected” or “not detected,” with possible sites of origin included if positive.
How it differs from traditional screening
“Traditional screening methods are designed to detect one type of cancer, like mammograms for breast cancer or colonoscopy for colorectal cancers,” says Dr. Klute. “Galleri is different because it’s looking for cancer in general. It can detect over 50 types of cancer, including many that don’t have recommended screening tests.”
The Galleri test appears to be particularly sensitive to fast-growing and more aggressive cancers, which are often the hardest to catch early with imaging-based methods.
“Those cancers tend to shed more DNA into the blood, which makes them easier for this kind of test to detect,” Dr. Klute explains. “The flip side is that it doesn’t perform as well for some slower-growing cancers, like many breast or prostate cancers.”
Reliability and false positives
About one in 100 people will test positive with the Galleri. Of those, roughly 50% will turn out to have a true cancer diagnosis. While it’s still improving, the false-positive rate remains a limitation of the test.
“We think that number will come down with longer-term follow-up,” Dr. Klute says. “Some of those initial false positives may represent cancers too small to detect on imaging at the time of testing.”
Because of this, repeat testing and follow-ups are recommended.
Who might benefit
The Galleri test seems to perform best in higher-risk populations, such as people over 50, those with a strong family history of cancer or those with known genetic mutations like BRCA or Lynch syndrome.
Lifestyle factors that increase baseline cancer risk, such as smoking, obesity or diabetes, may also make someone a better candidate. However, the Galleri testing should not replace traditional screening methods.
“A negative test doesn’t mean someone doesn’t have cancer,” says Dr. Klute. “It’s not a substitute for mammography, colonoscopy or other recommended screenings.”
Cost considerations
Most commercial insurers and Medicare don’t cover the Galleri test yet. The out-of-pocket cost through Nebraska Medicine is about $749, discounted from the standard price of around $900.
Patients may be able to use HSA or FSA funds, and some life insurance or employer plans have started covering it. As further research on Galleri testing matures, that coverage could expand. However, cost remains one of the biggest barriers to access.
Current research and what’s next
“The data we have so far shows that Galleri can detect cancers that wouldn’t otherwise be found through routine screenings,” says Dr. Klute. “That’s exciting, but we still need to know whether finding these cancers earlier actually helps patients live longer or improve cure rates.”
She references ongoing clinical trials:
- Pathfinder 1 & 2 studies show that the test can detect early-stage and otherwise undetected cancers.
- The NHS-Galleri trial in the United Kingdom and a Medicare-based U.S. study are now examining whether MCED testing leads to earlier diagnoses and better long-term outcomes.
“If those studies show that detecting cancers earlier translates to improved survival, that could have huge implications,” she says. “It could change how we screen, allocate resources and save lives.”
Takeaways for providers
“For now, this test is best suited for patients at a higher risk or those who are especially proactive about their health,” says Dr. Klute. “But it’s important to set expectations — it’s not a replacement for traditional cancer screening.”
Providers interested in offering Galleri testing can find additional clinical information and patient resources through the Grail website or by contacting Nebraska Medicine’s Cancer Risk and Prevention Clinic. Connect with a member of the cancer team by emailing physicianoutreach@nebraskamed.com.