Multi-Cancer Early Detection (MCED) Tests: What You Need to Know

Cancer death rates dropped by 34% from 1991 to 2023. Nevertheless, more than 626,000 people in the United States will die from the disease in 2026, according to American Cancer Society (ACS) projections.

To reduce cancer mortality even further, researchers are studying multicancer early detection tests (MCEDs), which can screen for dozens of cancer types in a single blood test. MCEDs are designed to detect markers in the blood that may signal cancer well before symptoms develop, thereby allowing for earlier detection and treatment when cancers are in more treatable stages.

“That’s what the promise is,” says Peter Mazzone, MD, Director of Cleveland Clinic’s Lung Cancer Screening Program who is spearheading its cancer early detection efforts. “The hope would be that we can find cancers before they have passed the point where they can be cured. The most important outcome would be fewer people dying from cancer because of these tests. That hasn’t been proven yet, but there’s hope and optimism.”

Despite the promise of MCEDs, questions about them remain, and like any cancer screening tests, they have pros and cons that you should discuss with your doctor.

How MCED Tests Work

As cells die or turn over, they shed DNA fragments, or cell-free DNA, into the bloodstream. Cancerous tumors also shed some of this cell-free DNA, or circulating tumor DNA.

MCEDs look for circulating tumor DNA, certain proteins in the blood, and/or specific genetic characteristics (e.g., methylation) that may signal that you have cancer cells somewhere in your body. MCEDs do not diagnose cancer, but they can alert you to the need for further diagnostic testing.

Several MCEDs are under study, such as the Galleri, Cancerguard, and Shield tests—to date, the Galleri test has perhaps the largest body of evidence about its use, Dr. Mazzone says. Your physician can order them, though—some companies offer online portals through which you can connect with a licensed provider to review details of the test and discuss your eligibility. You provide a blood sample, the blood is sent to a lab for analysis, and you receive the results in about 10 to 14 days, Dr. Mazzone explains.

“It’s important to note that none of these are yet FDA [U.S. Food & Drug Administration] approved or recommended in any particular medical society’s guidelines,” he adds. “But the uptake is increasing, and awareness of their availability is growing. That’s in part why we decided to develop an early cancer detection program, to steward their appropriate use.”

Potential Benefits of MCED Tests

Of the more than 100 types of cancer, standard-of-care screening is available for only prostate, colorectal, lung, breast, and cervical. MCEDs test for signals shared by multiple cancers, many of which have no standard-of-care screening available.

“All of the current screening tests reduce mortality due to those individual cancers. So, we know that screening works when you have an effective test, and yet we still lose more than 600,000 people a year due to cancer,” says Eric Klein, MD, distinguished scientist at Grail (developer of the Galleri test). “In the U.S., only 14% of all cancers are detected by screening and more than 70% of cancer-related deaths occur in unscreened cancers, so that’s what we’re trying to address.”

Research from Grail suggests that among people with no clinical suspicion of cancer, the Galleri test, when added to standard screening, can significantly increase the number of screen-detected cancers and identify about 40% of all cancers and nearly three-quarters of the 12 cancers responsible for two-thirds of cancer deaths in the United States (European Society of Medical Oncology Congress, October 2025). One study (SYMPLIFY) showed that for people with symptoms suggestive of cancer, more than one-third of them initially believed to have received false-positive results from the Galleri test were later found to have cancer after two years of follow-up, resulting in an increase in the test’s positive predictive ability from 75% to 85%.

In general, distant-stage, or stage 4, cancers are the most lethal, with only 35% of people with these cancers surviving at least five years after diagnosis. These cancers tend to shed more cell-free DNA into the bloodstream, making them more likely to be detected by MCEDs.

In a recent study, researchers developed a simulation model of 14 solid tumor types that account for 80% of cancer incidence and death. They concluded that annual MCED testing, combined with standard-of-care screening, could reduce stage 4 cancer diagnoses by as much as 45% over 10 years (Cancer, Nov. 15, 2025). Also, Grail recently reported preliminary results of an ongoing randomized clinical trial showing that although Galleri did not meet the trial’s primary endpoint of a reduction in stage 3 and 4 cancers over three years, use of the test was associated with a greater than 20% reduction in stage 4 cancers alone.

“If it’s very clear that there’s a reduction in stage 4 cancers and we see all the other data they collect through this, that would be a very promising sign to me, for sure,” Dr. Mazzone adds.

MCED Test Limitations and Risks

Along with the promise of MCEDs come some limitations and potential risks. For instance, since less aggressive and early-stage cancers do not shed much DNA, MCEDs might not detect them until they reach a later stage. Moreover, MCEDs are not foolproof—no cancer screening is—and they cannot identify all types of cancer.

All cancer screening tests can produce false-positive results, which can cause emotional distress and, in some cases, lead to further invasive diagnostic tests (and potential complications from them) when no cancer is there. However, data suggest that false-positive rates for MCEDs (0.4% for Galleri, 2.6% for Cancerguard and 1.4% for Shield) are much lower than those for standard-of-care screening tests. Furthermore, the positive predictive values (the probability that a person with a positive screening test has cancer) for MCEDs far exceed those of standard screening tests, Dr. Klein notes.

“The false-positive rate for all of the current standard-of-care screening tests overall is around 10%,” Dr. Klein says. “So, the big question is, what is the harm of getting an MCED test? The harms, based on the data, seem to be really small.”

Another concern is that a negative result from an MCED may provide a false sense of security that no cancer is present, thereby prompting some people to skip recommended standard-of-care cancer screenings. “MCEDs should complement, not replace, standard-of-care screening,” Dr. Mazzone cautions. “And because these tests do not find all cancers, don’t ignore any symptoms that come up. Please get them evaluated.”

At this point, a key limitation of MCEDs is that they’re not FDA-approved and insurance coverage for MCED tests is not widely available. The out-of-pocket cost of MCED tests can range from nearly $700 to about $950. (Recently approved federal legislation authorizes Medicare coverage for any FDA-approved MCEDs starting in 2028.) Plus, coverage of imaging studies and other follow-up tests that may be necessary after MCED testing can vary, so check with your insurance provider.

Who Should Consider MCED Testing?

Since advancing age is the most significant cancer risk factor, MCEDs are generally recommended for older populations (ages 50 to 79 for Galleri). The tests also should be considered for other individuals at increased cancer risk based on their personal or family history of the disease, certain genetic syndromes, or lifestyle habits like tobacco smoking.

“For right now, I think the focus should be on those populations,” Dr. Mazzone says. “As part of that, a comprehensive approach to early cancer detection is important, so make sure you’re up to date on standard-of-care screening.”

As with other cancer screening tests, engage in shared decision-making about MCEDs with your physician. Consider your overall health and life expectancy—you have to be healthy enough to benefit from screening, further testing and any treatments that a cancer diagnosis would necessitate—and then make the decision that’s right for you after carefully weighing the benefits and potential limitations (see “What You Should Know”).

“MCEDs are worth having a conversation with someone who has expertise to guide you about the potential benefits and downsides, at a time when we just don’t have perfect evidence to tell you absolutely yes or absolutely no,” Dr. Mazzone says. “I think there’s an in-between right now where it’s OK to get them, as long as it’s done in a very thoughtful manner, with a team that’s able to guide you and then manage the results of the test.”

What to Do If You Receive a Positive MCED Result

A positive MCED result warrants a diagnostic workup. Some MCEDs provide a cancer signal origin (CSO, the anatomic site in the body where the cancer originates), which guides decisions about the follow-up testing (for instance, a colorectal CSO would prompt a colonoscopy). If a CSO is not provided, a whole-body contrast-enhanced computed tomography (CT) scan is recommended, Dr. Mazzone says.

If the MCED result is negative, that doesn’t mean you’re cancer-free, so continue to undergo recommended standard-of-care cancer screenings at an interval your healthcare providers recommend. Grail recommends repeating the Galleri test annually, Dr. Klein says, but experts have yet to determine an optimal testing interval for MCEDs as a whole.

“I’m a cancer doctor, and I’ve spent my whole career treating cancer patients,” Dr. Klein says. “We lose over 600,000 people a year due to cancer, and that has not changed meaningfully over the course of my career. It’s not going to change unless we find cancer earlier. …Until we have some spectacular therapy, our path to reducing cancer mortality is early detection.”