Most cancers in the United States are caught too late — partly because millions of Americans have no routine screening option available to them at all. A newly published study suggests a single blood test could change that, scanning the body for signs of multiple cancers at the same time.
The research, published in the journal Nature Medicine, centers on a blood test designed to detect patterns of abnormal DNA fragments that may signal cancer. What makes it different from most existing cancer tests is its scope — rather than targeting one specific cancer type, it looks across the body for multiple cancers simultaneously.
Dr. Karthik Giridhar, a breast oncologist and translational researcher at Mayo Clinic who worked on the study, described the approach this way:
“A blood test that’s trying to add on to the existing screening paradigm and shifting how we normally think of cancer screening from one cancer at a time to looking in the blood for patterns of abnormal DNA fragments that can screen for multiple cancers at once.”
Most Cancers Have No Screening Test at All
The United States currently has established screening programs for only a handful of cancers — breast, cervical, prostate, and lung among them. But those represent a fraction of all cancer deaths. According to Dr. Giridhar, the majority of cancer fatalities in the U.S. come from types that have no standard screening tool.
That gap is where the new test shows the most promise. In the clinical study known as PATHFINDER 2, researchers found that two-thirds of the cancers identified by the test were types that had no existing screening method. Dr. Giridhar noted that the test performed especially well on cancers like head and neck cancers and hepatobiliary cancers — areas where doctors currently have little to no early detection capability.
A Complement to Existing Screenings, Not a Replacement
Dr. Giridhar was clear that this test is not meant to replace mammograms, colonoscopies, or other established screening methods. He said the evidence supporting those existing tools — in terms of long-term patient benefit — remains stronger, and they should stay the priority.
“It’s clearly something designed to add to existing testing, not to replace the current screening.”
For cancers like breast cancer, he acknowledged the new test did not perform as well as existing screenings. But from his perspective as a breast oncologist, that is acceptable precisely because mammography already exists. The new blood test fills gaps, not roles already occupied by proven tools. He envisions the two working in tandem rather than in sequence, with patients and their doctors deciding together whether adding this test makes sense.
How the Test Works
The test analyzes what are called methylation patterns in DNA fragments found in the bloodstream. These chemical markers differ between cancer types, allowing the test to do two things: flag whether there is a potential cancer signal, and indicate where in the body that cancer may be originating. That second capability — identifying the likely source of cancer — is critical for guiding doctors on where to look next.
In the PATHFINDER 2 study, that cancer signal origin was accurate 91% of the time, which Dr. Giridhar described as highly useful for clinical teams conducting follow-up evaluations. Across the study, researchers identified 17 broad cancer types covering 81 different cancer subtypes.
Balancing False Positives and False Negatives
One of the central challenges in designing any cancer screening tool is managing errors in both directions. A false positive — telling someone they may have cancer when they don’t — causes unnecessary anxiety and can lead to costly, invasive follow-up procedures. A false negative — missing a cancer that is actually present — can allow a disease to progress undetected.
Dr. Giridhar said the test was built with high specificity to minimize false positives. But he also offered a nuanced take on false negatives, noting that not all missed cancers represent the same level of concern:
“We are preferentially capturing the more aggressive disease biologies. What I don’t want to see happen is an overdiagnosis of the very slow-growing, the cancers you just observe and don’t treat anyways, because I don’t think we’re helping in that situation.”
He elaborated on the concept of overdiagnosis — the risk of detecting cancers so slow-growing that a patient would never experience symptoms or need treatment. In his view, finding those cases does more harm than good.
“Sometimes we describe it like the type of cancer somebody might die with rather than from. We don’t want to overdiagnose indolent disease, and this test is not doing that.”
Dr. Giridhar emphasized that the field of multi-cancer detection testing is still evolving rapidly. Researchers are exploring combinations of DNA fragment analysis, protein markers, and other approaches to improve accuracy and expand the range of detectable cancers. For patients and families who have long had no early warning options for certain diagnoses, this kind of progress represents a meaningful shift in what’s possible. You can follow related health and medicine coverage and additional reporting from science journalists tracking developments in cancer research. Reporting on this story was also shared via KJZZ’s The Show and discussed by Mark Brodie, with additional health stories covered by reporters including Lauren Gilger and Kathy Ritchie.
Other recent health stories from the region include coverage of an ASU professor’s startup offering neuro-optimized lighting for migraine sufferers, a report showing nearly 60% of Arizona Latinos view environmental conditions as a major health concern, the opening of a new primary care clinic in central Phoenix designed to serve older Latino patients, and reporting on a new Mesa clinic addressing gaps in health insurance coverage for Arizonans.
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