“No cancer signal detected.” The blood test results popped up in my online health portal without much fanfare. A doctor would chat about them with me later, congratulating me on the “phew”-worthy result.
I took the Galleri multi-cancer early detection (MCED) test about a year ago in 2024 as part of my longevity-focused stay at Canyon Ranch, a luxury wellness retreat in Tucson, Arizona. Galleri – which costs $949, and is not currently FDA-approved – is a blood test that studies DNA fragments shed into the bloodstream. Patients need a prescription before pulling up their sleeves.
GRAIL, the company behind Galleri, recently presented findings from a study across 25,000 healthy adults over the age of 50. The test, the company says, found cancers at earlier stages and in organs that don’t have routine screening. Galleri discovered cancer signals in 216 people, and 133 of them indeed had cancer. It also correctly predicted the cancer’s origin 92% of the time.
“We’re able to isolate those DNA fragments, sequence them and look for those tumor-specific markers from the blood,” says Megan Hall, the vice president of medical and corporate affairs at GRAIL. If a “cancer signal” is detected, it also provides a cancer signal origin prediction, or a clue to the providers and the patient which organ that signal could be coming from. If that origin was the pancreas, for example, doctors would know where to start looking for the possible cancer.
“The key plain takeaway: (This type of testing) may complement current screening by identifying lethal cancers that are otherwise undetected earlier and with limited downstream burden,” says Dr. Mohamed Abazeed, chair and professor of radiation oncology at Northwestern University, who was not involved with the study.
The big question: Is this the future of cancer treatment? A simple blood test? It’s not that easy. The new research from the company, while promising, isn’t going to get you out of your recommended colonoscopies and mammograms.
‘Just waiting to find’ these hidden cancers
Multiple companies are trying to detect cancer via blood test. But GRAIL is the one you’re hearing about in the mainstream thanks to its funding of large, international prospective clinical trials.
“It was clear to me, as we were running the study, that we were picking up some novel cancers at an early stage that we previously had no means of detecting,” says Dr. Nima Nabavizadeh, a radiation oncologist at the Oregon Health and Science University and author of GRAIL’s Pathfinder 2 study presented at the European Society for Medical Oncology Congress in October.
We only widely screen for five cancers in the United States: breast, colorectal, prostate, cervical and lung cancer, the latter in only high-risk patients. But 70% of cancer deaths come from those without a recommended screening test. That’s where Galleri hopes to split the difference.
Is the Galleri blood test the future of cancer treatment? It’s not that simple. The new research from the company, while promising, isn’t some cure-all.
“These are largely cancers that we’re normally, outside of these blood tests, just waiting to find them, either incidentally or because somebody has symptoms associated with them,” Nabavizadeh says.
The test doesn’t pick up some cancers as well, like prostate cancer, though there’s already an effective diagnostic tool for that known as the PSA test. Why does Galleri detect certain cancers better than others? Some shed more DNA than others, i.e. head and neck and pancreatic cancers versus prostate.
Interest in the test has grown: More than 15,000 healthcare providers have prescribed it, and health systems like Rush University Health System in Chicago, Community Health Network in Indiana and Mercy in Missouri offer it, too.
Dr. Elizabeth O’Donnell, director, of the Multi-Cancer Early Detection Clinic at Dana-Farber Cancer Institute, says this testing is “a really good starting point for potentially addressing a massive unmet need in medicine.”
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‘A positive blood test is not a diagnosis’
Beware that Galleri does and can pick up indolent cancers – i.e. slow-growing ones like Chronic lymphocytic leukemia – which you and your provider may decide not to treat, or just keep an eye on.
“We want to make sure that we are detecting those more aggressive cancers that really do warrant treatment,” says Hall.
Overall, doctors both involved with and not involved with the study aren’t concerned about the Galleri test and overdiagnosis, or sending people down a path of unnecessary endless treatment. About 1% of people receive a positive cancer detection signal, which means 99% live their lives and go about their normal recommended screenings.
But “a positive blood test is not a diagnosis,” says Gilberto Lopes, MD, chief of medical oncology with Sylvester Comprehensive Cancer Center, part of the University of Miami Health System. “You still need imaging, sometimes a biopsy. That takes time and resources.” Health systems and providers need to prepare for patient questions and anxiety, too, especially regarding positive results.
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The uncertain FDA approval path for Galleri
GRAIL is bullish about FDA approval for Galleri, which could make it more accessible if private insurers and Medicare reimburse doctors for running the tests. But according to Abazeed, the FDA will want to see evidence that earlier detection means fewer late-stage cancers or a reduced risk of death. And that still isn’t available.
If the data bears out, it’s a game-changer. But “real-world implementation, however, will require more including standardized diagnostic algorithms, confirmatory imaging and biopsy and proper safeguards to ensure consistent follow-up,” Abazeed says.
Something must change when it comes to cancer care, O’Donnell says. Sure, people are living longer with cancer, but cures come when you find diseases early. “Anybody who’s been in practice long enough knows that we need to be doing something differently,” O’Donnell says.
My negative results didn’t surprise me. I wasn’t exhibiting cancer symptoms and the test is geared toward those 50 and older anyway (I was 32 at the time), given that age is the biggest risk factor for developing cancer. But it was still nice to know that a deadly cancer wasn’t hiding in a random organ.
Before you take the test yourself, make sure you read up on all the caveats and chat with a trusted healthcare provider first. The “no cancer signal detected” sentence was comforting for me and the other 99% – but not a lifetime guarantee.
This article originally appeared on USA TODAY: Galleri early cancer detection blood test: I tried it.