Can a blood test find cancer?

You’re scrolling through your social feed. Between updates from family and friends, you spot a headline about a new blood test for cancer. Later you see a video of your favorite influencer getting their blood drawn. Their message: Get screened!

You might be thinking: What’s the deal with blood tests? And why are they everywhere right now?

Blood tests are powerful tools, and their use throughout cancer care from screening to surveillance is growing. Understanding what these tests are, who they’re for, and both their potential and limitations is increasingly important for those looking to take charge of their health.

Let’s start with the basics.

What are blood-based cancer tests?

There are multiple types of blood-based tests used in cancer care. Some examples include:

• Single-organ screening tests: These tests screen for cancer that originates in a specific organ, like the colon.
• Multi-cancer early detection (MCED) tests: These tests can find signals from multiple cancer types that can begin in various parts of the body.
• Treatment guidance tests: These tests can provide personalized insights to inform treatment decisions.
• Molecular residual disease tests (MRD): These tests can find signs of residual cancer after treatment to understand recurrence risk and help guide care.

How do blood tests find cancer?

Our blood is busy. It carries oxygen and nutrients throughout the body, delivers waste products to the liver and kidneys, and supports our immune response. It’s full of biological matter including white and red blood cells, platelets, proteins, water and salt. And — in some cases — subtle signs of cancer. 

That’s where blood tests come in. Blood-based cancer tests are designed to distinguish cancer signals, or biomarkers, from the rest of your blood’s contents, providing insight into the potential presence of disease.

Who can use a blood-based cancer screening test?

Blood-based cancer screening tests are designed for asymptomatic individuals who meet other test-specific criteria, like age. Your doctor can help you determine if this option is right for you.

If I take a multi-cancer early detection test, can I skip other cancer screenings?

Multi-cancer early detection tests are meant to complement, not replace, routine cancer screening. However, around 70% of annual cancer cases and deaths have no recommended screening.¹ By looking for signals from multiple cancer types at a time, MCED tests can help find cancers that may otherwise only be discovered much later,² perhaps when someone experiences symptoms.

Can a blood test help me if I already have cancer?

If you have cancer, treatment guidance tests can help you understand your unique risk profile and help you and your doctor make personalized decisions about your care.

After treatment, molecular residual disease (MRD) tests can detect the continued presence or return of disease — sometimes years before standard methods,³ like a CT scan. These tests can be tumor-naïve and look for general biomarkers associated with your cancer type. Or they can be tumor-informed and search for the unique markers of your specific cancer.

What do I need to consider before using a blood test?

New blood tests are expanding options for cancer screening and monitoring. While rapidly evolving technology drives headlines, the hype surrounding them can gloss over important considerations:

• How accurate is the test?
• How early does it find cancer?
• How often will I have to take the test?
• Is the test performance backed by strong evidence?
• What support comes with the test?

Understanding what these tests can — and can’t — do is an important part of advocating for yourself and your health. The next best step is to talk to your doctor to identify the test that’s right for you.

References

¹ Siegel RL, Kratzer TB, Wagle NS, et al. Cancer statistics, 2026. CA Cancer J Clin. 2026;e70043.

² Cancerguard Clinician Brochure. Abbott Laboratories. Madison, WI.

³ Diergaarde B, Young G, Hall DW, et al. Circulating tumor DNA as a marker of recurrence risk in Stage III colorectal cancer: The α‐CORRECT study. J Surg Oncol. 2025;132(1):175-186.