A Cancer Blood Test Shows Promise — But Is it the Breakthrough Clinicians Were Waiting For?
Early cancer detection can mean the difference between a quick treatment and a life-changing diagnosis. For decades, doctors and scientists have chased the same goal: a simple blood test that could flag cancer early, long before symptoms show up.
Then Theranos happened, the health tech start-up fabricating that they developed a revolutionary device testing small amounts of blood for a wide range of diseases and conditions, reminding everyone that promising the future is easier than building it.
Now, nearly a decade later, a new generation of biotech companies is daring to try again. One test in particular, called Galleri, is getting serious attention after a large new clinical study showed it could dramatically increase cancer detection when used alongside routine screenings like mammograms and colonoscopies.
This warrants the question: Is this the cancer blood test medicine has been waiting for?
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Cancer Detection Sevenfold
Galleri is a “multi-cancer early detection” (MCED) test developed by GRAIL, Inc. The latest data to display the test’s ability comes from an extensive study called PATHFINDER 2, which enrolled nearly 36,000 adults age 50 and older across the U.S. and Canada. These weren’t people who already suspected they had cancer, but a real-world screening population. Researchers analyzed results from the first 25,000+ participants who had at least one year of follow-up.
The result was that when Galleri was added to routine cancer screening, overall cancer detection jumped more than sevenfold. Even more encouraging, more than half of the cancers Galleri detected were early-stage, when treatment is simpler, more effective, and often lifesaving.
Additionally, three-quarters of the cancers Galleri detected have no standard screening tests today. Right now, U.S. guidelines routinely screen for only a handful of cancers (like breast, colon, cervix, and lung), although about 70 percent of cancer deaths come from cancers we don’t regularly screen for, explained Nima Nabavizadeh, M.D., and associate professor of Radiation Medicine at Oregon Health & Science University, in a press statement.
Galleri also proved surprisingly good at one critical task: pointing doctors toward the right body system. In the trial, it correctly identified where the cancer signal was coming from 92 percent of the time, helping doctors choose imaging and follow-up tests faster instead of casting a wide net.
Blood Test Won’t Replace Mammograms and Colonoscopies
False positives and false negatives happen with all screening tests, including this one. Gilberto Lopes, M.D., and chief of medical oncology with Sylvester Comprehensive Cancer Center, told USA Today that a positive result doesn’t always mean you have cancer. And a negative one doesn’t guarantee you don’t.
If Galleri flags a possible cancer signal, doctors still need imaging scans, lab tests, and sometimes biopsies to confirm it. That means time, money, and anxiety for patients waiting on answers, Lopes said.
Currently, the test is recommended for adults 50 and older, particularly those with a higher cancer risk. And it’s prescription-only, meaning your doctor has to order it and help interpret the results based on your health history. Galleri also doesn’t replace standard screening. Mammograms and colonoscopies are still your first line of defense.
Doctors Feel Positive About New Cancer Blood Test
So far, the safety profile looks encouraging. In the study, no serious medical events were linked to the test itself or the diagnostic follow-ups. The company plans to submit this data to the FDA to gain approval for broader use. If insurers and Medicare eventually agree to reimburse the test, it could become much more accessible.
Doctors are cautiously optimistic. Cancer specialist Mohamed Abazeed, who wasn’t involved in the research, summarized in USA Today that Galleri may help identify deadly cancers that otherwise slip through the cracks, without overwhelming patients or health systems with unnecessary testing.
Adoption is already growing. More than 15,000 clinicians have started prescribing it, and hospital systems in states like Illinois, Indiana, and Missouri now offer it. For patients who’ve been waiting decades for better early warning signs, this may finally be a step toward a future where cancer doesn’t get the first move.
This article is not offering medical advice and should be used for informational purposes only.
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