Seventy-one percent of cancer deaths come from types we don't screen for
At the edge of a long-standing gap in medicine, Mayo Clinic began offering a single blood draw capable of scanning for more than fifty types of cancer — including many that have historically remained invisible until too late. Developed by GRAIL and called the Galleri test, it reads the faint genetic signatures that tumors leave behind in the bloodstream, offering a new form of vigilance for patients at elevated risk. The test does not replace the tools already in use, but it reaches into a silence that has long cost lives — the seventy-one percent of cancer deaths that arise from cancers no standard screening has ever reliably caught.
- Seventy-one percent of cancer deaths come from tumor types that have no recommended screening protocol — a gap the Galleri test is designed to directly confront.
- The test sequences tumor DNA fragments circulating in the blood, flagging cancer signals with a false positive rate below one percent — a level of precision that gives clinicians real reason to act.
- Despite its promise, the $949 price tag and lack of insurance coverage create an immediate barrier, limiting access to those who can afford it and have a doctor willing to prescribe it.
- FDA approval remains pending, and Mayo Clinic is positioning the test as a complement to existing tools like mammograms rather than a standalone solution — managing expectations while building clinical momentum.
- If approval is granted and adoption spreads, the test could fundamentally shift cancer medicine from reactive treatment toward early interception for diseases that have long defied early detection.
By the close of 2021, Mayo Clinic was preparing to offer a blood test that could screen for more than fifty types of cancer in a single draw. The test, developed by GRAIL and called Galleri, works by detecting fragments of tumor DNA that cancer cells shed into the bloodstream — genetic signatures that, when sequenced and analyzed, can reveal a malignancy before symptoms ever appear.
The clinical case for the test rests on a troubling reality: the American Cancer Society has found that seventy-one percent of cancer deaths come from types for which no standard screening exists. Mammograms and colonoscopies have long served their respective domains, but cancers of the pancreas, ovaries, and many other organs typically go undetected until they are already advanced. In a study involving Mayo Clinic and other institutions, researchers identified twenty cancer signals among 6,600 participants, with false positives occurring less than one percent of the time.
Doctors were deliberate in framing the Galleri test as an addition to existing care, not a replacement for it. It was designed for high-risk patients — those with family history, genetic markers, or other elevating factors — and would require a physician's prescription. At $949 per test, with no insurance coverage, access would not be universal.
FDA approval was still pending, but the data suggested a clear path forward. If granted, the test could enter clinical practice before year's end, beginning to close a detection gap that has quietly shaped cancer mortality for generations.
Mayo Clinic was preparing to introduce a blood test capable of identifying more than fifty varieties of cancer by year's end 2021, marking what many in the medical field saw as a significant shift in early detection strategy. The test, developed by a company called GRAIL and branded as the Galleri test, works by identifying fragments of tumor DNA that cancer cells shed into the bloodstream. Rather than waiting for symptoms or relying on imaging studies, doctors could now order a single blood draw and screen for malignancies that have historically gone undetected until they were already advanced.
The science behind the approach is straightforward in concept but sophisticated in execution. Cancer cells leave behind genetic signatures in the blood—tiny pieces of DNA that circulate through the body. Dr. Julia Feygin, speaking to CBS Minnesota, explained that the test sequences these fragments and analyzes the patterns they form. If a cancer signal emerges from that pattern analysis, the test flags it. In a clinical study involving Mayo Clinic and other institutions, researchers identified twenty cancer signals among 6,600 participants. A separate analysis showed the test produced false positives less than one percent of the time, a level of accuracy that suggested real clinical utility.
The potential impact is substantial because of a stark gap in current cancer care. The American Cancer Society has documented that seventy-one percent of cancer deaths come from tumor types for which no standard screening protocols exist. Mammograms catch breast cancer. Colonoscopies find colorectal disease. But for many other malignancies—pancreatic, ovarian, and others—patients typically learn they have cancer only after symptoms appear, often when the disease is already in advanced stages. A blood test that could catch these cancers earlier, before they spread, could reshape survival rates.
Doctors were careful to frame the test as a complement to existing screening methods rather than a replacement. Dr. Feygin noted that the Galleri test would work alongside mammograms and other established tools, not instead of them. The test was designed for people at elevated risk—a category that could include those with a family history of cancer, certain genetic markers, advanced age, or other health factors. It was not intended as a universal screening tool for the general population.
Practical considerations shaped how the test would reach patients. Mayo Clinic planned to charge $949 per test, and insurance companies would not cover the cost. A doctor's prescription would be required, meaning patients could not simply order it themselves. The makers of the test were still pursuing full approval from the Food and Drug Administration, though early data suggested the pathway was clear. If regulatory approval came through as expected, the test could enter clinical practice before the year ended, beginning to address the detection gap that had long plagued cancer medicine.
Notable Quotes
If cancers can be detected early, we can dramatically improve patient outcomes— Dr. Julia Feygin, Mayo Clinic
We can find and sequence these tiny bits of tumor derived DNA in the blood and based on the patterns we see we can reveal if there is a signal for cancer present— Dr. Julia Feygin
The Hearth Conversation Another angle on the story
Why does a blood test matter so much when we already have screening tools like mammograms?
Because mammograms only catch breast cancer. Seventy-one percent of cancer deaths come from types we don't screen for at all. A pancreatic cancer patient usually finds out when it's already spread. This test could catch it years earlier.
How does it actually work? What's it looking for in the blood?
Cancer cells are shedding DNA fragments into your bloodstream all the time. The test sequences those fragments and looks for patterns—signatures that say a tumor is present. It's like reading a fingerprint left behind by cancer cells.
Is it accurate?
Less than one percent false positive rate in the studies. That's extremely reliable. But they found twenty signals in 6,600 people, so it's not catching everything either. It's a tool, not a guarantee.
Who gets to use it?
People at elevated risk—older patients, those with family history, certain health conditions. It's not for everyone. And it costs $949 out of pocket, no insurance coverage yet.
So it's not replacing mammograms?
No. It works alongside them. Doctors see it as filling gaps where no screening exists, not replacing what already works.
What happens next?
FDA approval is pending. If it comes through, Mayo Clinic and other institutions start using it routinely. That's when you'd see real impact on survival rates.