Can cancer be identified through a simple blood test? MCEDs explained
Imagine being able to check for multiple types of cancer through a single blood test. Science fiction, or the wave of the future?
"Science has been moving at lightning speed," says Rachael Brandt, PhD, MS, LCGC, Manager of Main Line Health's Genetics and Risk Assessment Program. "While doctors have been using blood-based tests to assess prognosis or recurrence in people with a known cancer diagnosis, blood tests that can screen for cancer in people without a known diagnosis are becoming available. While there are still some limitations with how these tests work, they offer promise for early detection."
How MCED tests work
Multi-cancer early detection tests, or MCED tests, are designed to detect DNA shed by cancer cells into the blood or other body fluids like urine or saliva. Most MCEDs currently available are blood-based tests.
While MCED tests can’t diagnose cancer, they can screen for “cancer signals,” which are biological patterns that may indicate the presence of specific cancers. These signals can help distinguish cancer cells from healthy cells and may provide clues about where the cancer originated. When a cancer signal is detected, the MCED test can help guide clinicians toward appropriate diagnostic evaluation.
Recommendations on usage are still unclear
MCEDs are not currently approved by the Food and Drug Administration (FDA), and they are generally not covered by insurance. Also, it can be challenging to interpret what MCED test results might mean, as you could have a false positive or negative.
"If your test comes back with 'no cancer signal detected,' it's less likely you have an active tumor in your body," says Hannah Gutierrez, MS, LCGC, certified genetic counselor in the Genetics and Risk Assessment Program. "But you could have an early-stage tumor that is not shedding DNA yet, so it may not be truly negative.
"And if your test comes back positive for a cancer signal," Gutierrez continues, "it's possible you might not have cancer. At that point, it's essential to have further tests like MRIs or additional blood tests to see if you have a tumor, and then to collaborate with a clinician on a care plan."
What may be possible in the future
Dr. Brandt notes that, while there are still questions around the use of MCEDs, there is hope overall.
“Currently, we only screen routinely for five types of cancer: breast, colorectal, cervical, lung and prostate,” Dr. Brandt explains. “If these new MCEDs are proven to help pick up other types of cancer, ideally in early stages when they are most treatable, this screening approach could be a game changer.”
For now, MCED testing does not replace standard cancer screening, even when no cancer signal is detected. People should continue to follow standard screening guidelines.
Can blood work detect cancer or a tumor?
Routine blood work that may be part of your annual physical doesn’t typically detect cancer or tumors. However, certain blood tests can help identify signs that may be associated with cancer. Newer multi-cancer early detection (MCED) blood tests can screen for some cancer signals in blood, but they cannot diagnose cancer. A positive result requires follow-up testing, and these tests do not mean you can skip recommended cancer screenings.
What kinds of cancers can MCEDs potentially find?
MCEDs can screen for multiple types of cancer at once, such as cancers of the:
Many of these cancers don’t have screening options, so you would only get a diagnostic test if you already have signs, symptoms or significant risk factors. But the potential of MCEDs is they could detect these cancers before symptoms develop and start treatment earlier.
Who should get an MCED
The medical community is still figuring out who is best to have these tests, especially since they are not yet FDA-approved. MCED testing may perform better when there's a higher risk for cancer, such as in people:
- Age 50 years and older
- With personal risk factors
- With a history of cancer in their family or an inherited cancer-related gene
More research is needed before these tests can be recommended for widespread use in people with no symptoms of cancer.
Should I take an MCED test to determine my chances of getting cancer?
If you are concerned about your chances of developing cancer, start by contacting the Genetics and Risk Assessment Program by calling 1.484.565.GENE. We can look at your family tree as well as other risk factors, and review options for genetic testing, cancer prevention and cancer screening, which may include MCEDs.
Should I take an MCED test if I have cancer symptoms?
No. If you have symptoms you think may be due to cancer, promptly discuss your concerns with your primary care clinician or make an appointment with a cancer care provider.
Who should not get an MCED?
Because MCED testing has not been well studied in certain populations and may be more likely to produce misleading results, it is generally not recommended for people who:
- Are currently pregnant
- Are age 21 or younger
- Have had cancer treatment within the past three years
- Have symptoms of cancer
- Are undergoing active cancer treatment
For example, pregnancy can make MCED results more difficult to interpret because both maternal and fetal DNA are present in the bloodstream. And people with cancer symptoms or those currently being treated for cancer typically need diagnostic testing and clinical evaluation rather than a screening test.
If you’re in one of these groups, talk with your clinician about whether MCED testing is appropriate for your personal situation.
Why is early detection important?
Cancers that are found early, before symptoms appear, can be more successfully treated, and there are more treatment options. Research is still underway to determine how effective MCED tests are at finding cancer early.
Why aren’t MCEDs FDA-approved?
When a medical test is FDA-approved, it means the FDA has reviewed the scientific evidence and determined that it is safe, effective and reliable. Currently, validation studies are trying to determine if these MCED tests really are finding cancer early, and whether they impact better survival.
The FDA’s studies of MCEDs are looking at:
- The frequency of:
- False negatives, or finding no cancer signal when cancer really is present
- False positives, or finding a cancer signal when no cancer is present
- How effective the test is at picking up early-stage cancers
- How these tests may impact treatment and survival rates
- Which cancer types are not detected by MCEDs
The timing of FDA review and approval is uncertain and depends on ongoing clinical research, regulatory review and additional evidence demonstrating clinical benefit.
Even though more research is needed to better understand MCEDs, they are currently clinically available as lab-developed tests, meaning people can request these tests through their doctors (without having to enroll in research trials). Galleri® and Cancerguard™ are two examples of available MCED tests.
Are MCEDs covered by insurance?
For any test to be covered by Medicare, it must be FDA-approved. Because the FDA does not yet approve them, Medicare doesn’t cover MCED tests.
Some private insurance plans may cover the cost of MCED tests for people with certain risk factors. Coverage varies by insurer and plan.
And a positive MCED result does not guarantee your insurance will pay for additional cancer testing, such as a biopsy, CT scan or MRI. Coverage for follow-up testing can vary depending on your insurance plan, your medical history and your doctor's recommendations.
Before having an MCED test, talk with your clinician and insurance company about potential costs and coverage for both the test itself and any follow-up care that may be needed.
What does an MCED cost?
Right now, the cost for MCED testing can be up to $750. You may be able to use your flexible spending account (FSA) or health savings account (HSA) to pay for MCED testing.
How do I get an MCED test?
The MCED test must be ordered by a physician. At Main Line Health, you can discuss MCED testing with:
- Your primary care physician
- A specialist in our Genetics and Risk Assessment Program by calling 1.484.565.GENE
How long does it take to get the MCED results?
Results are available in approximately two weeks.
What happens when I get the MCED results?
No matter if the results from your MCED testing are positive or negative, they should be reviewed with a clinician.
If you receive a “cancer signal detected” result, we strongly encourage you to follow up with your health care provider. They will collaborate on a plan of care for additional testing and appointments with specialists to determine if cancer is present and, if so, the type and location.
If your result is negative, it’s still important to discuss next steps for follow-up.
If I have a negative MCED result, can I skip other tests like a colonoscopy or mammogram?
No. MCEDs are meant to be used in addition to standard screening tests, not in place of them. You should keep up with standard screenings recommended by your health care provider, which may include:
- Mammograms for breast cancer
- Colonoscopies and other colorectal cancer screening tests, including at-home options
- Pap smears and HPV tests for cervical cancer
- CT scans for lung cancer
- PSA tests for prostate cancer, when appropriate
You could still have cancer even with a negative MCED, especially if it’s an early-stage cancer. An MCED is only a snapshot in time; research is still ongoing about how often MCED testing should be repeated.
What about urine tests for finding cancer?
Because some types of cancer are not well-detected by blood-based DNA screening tests, researchers are also investigating the effectiveness of evaluating DNA signals that may be found in urine. While research is promising, urine-based cancer tests aren’t as well studied as MCEDs yet.
If you're interested in emerging cancer detection technologies, talk with your health care clinician about which testing options may be appropriate for your personal risk factors and medical history.
More to come
The fate of MCEDs and what they mean for cancer care is an evolving story. Check back regularly for updates.
Next steps
Meet Rachael Brandt, PhD, MS, LCGC.
Meet Hannah Gutierrez, MS, LCGC.
Learn more about the Genetics and Risk Assessment Program.
Learn more about Main Line Health Cancer Care.
Related posts
Jessica's story: Genetic testing revealed a lifesaving surprise
Content you want, delivered to your inbox
Want to get the latest health and wellness articles delivered right to your inbox?
Subscribe to the Well Ahead Newsletter.
