Multi-Cancer Early Detection (MCED)

Multi-Cancer Early Detection (MCED) refers to a category of screening tests designed to look for signals associated with multiple types of cancer at the same time, often using a single blood sample. These tests aim to detect potential cancer-related markers before symptoms appear, which may help identify cancer earlier than traditional cancer screening methods. MCED tests are not diagnostic. Instead, they are intended to provide early insight that may prompt additional clinical evaluation or follow-up testing with a healthcare provider.

How MCED Tests Work

Most Multi-Cancer Early Detection (MCED) tests are a type of liquid biopsy, meaning they analyze biological signals found in blood or other body fluids. These signals may be associated with cancer and can include:

• Fragments of genetic material, such as DNA or RNA, are shed by cells
• Molecular or epigenetic patterns that differ between healthy and cancer cells
• Proteins or other biomarkers that may be present at different levels in cancer

Advanced analytical techniques, often including machine-learning–based models, are used to assess whether these signals resemble patterns associated with certain cancers. Depending on the specific test, an MCED result may also suggest a likely tissue or organ of origin, or it may simply indicate that a cancer-associated signal was detected. In all cases, additional diagnostic testing is required to determine whether cancer is present and, if so, to confirm its type and location.

How MCED Differs from Traditional Cancer Screening

Traditional cancer screening typically focuses on one cancer at a time, such as breast, colorectal, or cervical cancer, using tests designed for a specific organ or tissue.

Multi-Cancer Early Detection (MCED) tests differ in that they aim to screen for multiple cancer types simultaneously, often using a single blood sample. Key differences include:

• Broader scope: Depending on the test, MCED may screen for anywhere from a few to dozens of cancer types at once. However, no single MCED test screens for all cancers.
• Single sample: Many MCED tests require only one blood draw, rather than separate tests for each cancer type.
• Complementary role: MCED testing is intended to supplement and not replace existing guideline-recommended cancer screenings, such as mammograms, colonoscopies, or Pap tests.

Because MCED testing is still an evolving area of medicine, these tests are generally viewed as an additional layer of insight rather than a substitute for established screening recommendations.

Is MCED FDA-approved?

At the time of publishing this, there is no multi-cancer early detection (MCED) test that is FDA-approved or recommended as a standard cancer screening tool for the general population. Some MCED tests are currently offered as laboratory-developed tests (LDTs) and are performed in CLIA-certified laboratories, which are regulated under federal laboratory quality standards. The U.S. Food and Drug Administration (FDA) continues to evaluate how best to regulate MCED technologies as additional research and clinical data become available.

Since MCED testing is still an emerging area of medicine, regulatory oversight, clinical guidance, and potential use cases may change as evidence evolves. People considering MCED testing may wish to review a test’s regulatory status, limitations, and follow-up process with a healthcare provider as part of an informed decision-making discussion.

How MCED Test Results May Be Reported

The way MCED test results are reported can vary by test. For example, the Galleri® test, one of the more widely studied multi-cancer early detection tests, reports results using signal-based language such as:

• No cancer signal detected, meaning the test did not identify cancer-associated biological patterns in the sample at the time of testing.
• Cancer signal detected, meaning the test identified biological patterns that may be associated with cancer and may warrant further clinical evaluation.

Other MCED tests may use different reporting formats or terminology, and not all tests attempt to suggest a tissue or organ of origin. Regardless of the reporting approach, MCED results do not diagnose cancer and require follow-up diagnostic testing to determine their clinical significance.

Key Limitations of MCED Testing

While MCED tests represent a promising area of cancer screening research, they have important limitations that should be clearly understood:

• MCED tests are not diagnostic: They cannot confirm whether cancer is present. Any finding that suggests a potential cancer-associated signal requires follow-up diagnostic testing, such as imaging or biopsy, to determine its cause.
• They do not detect all cancers: The number and types of cancers assessed vary by test, and some cancers may not release detectable signals into the blood at the time of testing.
• A negative result does not rule out cancer: MCED testing reflects a snapshot in time and may miss cancers that are very early, slow-growing, or not shedding detectable signals.
• False-positive and false-negative results are possible: As with other screening tools, MCED tests may indicate an abnormal signal when cancer is not present, or fail to detect cancer when it is present.
• MCED tests do not replace established cancer screenings: They are not a substitute for guideline-recommended tests such as mammograms, colonoscopies, Pap tests, or low-dose CT scans for lung cancer.

What Happens After an MCED Result

What happens after an MCED test depends on the result and the individual’s clinical context.

If a potential cancer-associated signal is identified, the next steps may include:

• Reviewing the result with a healthcare provider
• Additional diagnostic evaluation, such as imaging or laboratory testing
• Referral to a specialist, depending on the suspected tissue or organ involved and the individual’s medical history

If no cancer-associated signal is identified:

• Routine cancer screenings should continue according to existing guidelines
• Regular medical care and preventive health visits remain important
• MCED results do not change current screening recommendations

An Example of an MCED Test Currently Available

Several multi-cancer early detection tests are currently available through specific clinical pathways. One example is the Galleri® Multi-Cancer Early Detection Test, which is offered as an in-person blood test collected via venipuncture.

The Galleri test analyzes fragments of DNA shed by cancer cells to look for biological patterns that may be associated with cancer. According to published study data, the test is designed to screen for signals linked to 50 or more cancer types, including some cancers that do not currently have routine screening options.

When a cancer-associated signal is detected, Galleri test results may also include a predicted cancer signal origin, which is intended to help guide follow-up diagnostic evaluation by a healthcare provider. As with all MCED tests, Galleri does not diagnose cancer and requires additional testing to confirm any findings.

The Galleri test is performed in a clinical setting and may be ordered by a healthcare provider. Availability, eligibility, and follow-up care can vary, and individuals considering this test should review its regulatory status, limitations, and intended use as part of an informed discussion with a healthcare professional.

Learn more about the Galleri® Multi-Cancer Early Detection Test available through Everlywell.

FAQs

Is MCED testing the same as a cancer diagnosis?

No. MCED tests are screening tools and cannot diagnose cancer. They are designed to look for biological signals that may be associated with cancer, not to confirm whether cancer is present. Any abnormal or concerning finding requires follow-up diagnostic testing, such as imaging or biopsy, to determine its cause.

Does MCED testing replace mammograms, colonoscopies, or Pap tests?

No. MCED testing does not replace guideline-recommended cancer screenings. Established screening tests remain the standard of care for cancers where routine screening is available, and MCED testing is generally discussed as a potential supplement, not an alternative.

Does MCED testing detect all cancers?

No. The number and types of cancers screened vary by test, and no MCED test detects all cancers. Some cancers may not shed detectable signals into the blood at the time of testing, particularly in very early stages.

Is MCED testing FDA-approved?

At this time, there is no FDA-approved MCED test recommended for routine population-wide cancer screening. Some tests are available through specific regulatory pathways while additional data are being collected.

Is MCED testing still being studied?

Yes. MCED testing is an active area of research, with ongoing studies examining test performance, appropriate use, and how results should be integrated into clinical care. Evidence and guidance may change as new data emerge.