The unscreened crisis

Screen better

Current screening guidelines save thousands of lives annually by catching cancer early. But they only cover 14% of cancers—a fraction of the diseases that threaten us. Imagine if we could detect more cancers before they stop us? 💪 Multi-cancer early detection (MCED) tests like the Galleri test are trying to normalize early detection and catch the cancers that are usually missed. But is it too good to be true?

Let’s dive in.

The screening landscape

To date, only five cancers have screening recommendations: breast, cervical, colorectal, prostate, and lung cancer. 

🔞 Age is the biggest risk factor for cancer. Risk goes up 13-fold after age 50, according to information published on the Galleri website.

Current recommendations for the age to start screening:

• Cervical cancer: Age 25

• Breast cancer: Age 45 (can begin at 40, depending on risk)

• Colorectal cancer: Age 45

• Prostate cancer: Age 45 (African Americans)

• Lung cancer: Age 50+

Of 600,000+ cancer cases in the U.S., most are not caused by cancers with screening recommendations, says Megan P. Hall, a scientist and the VP of Medical and Corporate Affairs at GRAIL (who developed the Galleri test) at the 2025 Livelong Experience in Palm Beach.

Plus, more than 70% of cancer deaths are caused by cancers without recommended screenings, according to statistics published by Galleri.

How does Galleri work?

Galleri is a blood test that looks for cancer DNA (‘fingerprints’) present in the blood stream. The test analyzes methylation patterns of DNA, which may indicate the location of the cancer, GRAIL explains.

• Methylation is neither good or bad. While it can help to rid the body of toxins, support immune health and energy, balance mood, and reduce inflammation, disrupted methylation processes can lead to disease, including cancer.

“By combining next-generation genome sequencing and machine learning, MCED tests can detect multiple cancer types, including those that are insufficiently prevalent to allow for efficient single-cancer screening,” write authors in an article in Nature.

_{*Epigenetic markers control the switches that turn genes on or off.}

Early-detection blood testing ≠ routine bloodwork

The most obvious difference between the Galleri test and routine blood work is that “most cancers don’t show up in routine blood work,” Cleveland Clinic writes.

Let’s take a look at a type of routine blood test called a complete blood count (CBC).

✅ What can routine bloodwork do:

• It can detect blood or immune system cancers, in some instances.

❌ What can’t routine bloodwork do:

• It does not detect solid organ cancers (Breast exams, prostate exams, and colonoscopies fill in some—but not all—of the gaps).

MCEDs are one of the few types of blood tests that can diagnose cancer at the early stages. Why? It is a liquid biopsy. Unlike a traditional biopsy, it doesn’t test the tumor directly; instead, it looks for tumor DNA or cells in the blood, which can indicate cancer.

Is Galleri effective at identifying cancer?

It may be an effective tool for detecting cancer (shows up as ‘Cancer Signal Detected’), depending on factors such as sensitivity and early detection rate.

Sensitivity: Sensitivity describes how accurately a test can identify someone with a disease. The test achieves approximately 76% sensitivity in detecting 12 of the most lethal cancers.

The mammogram—the gold-standard screening tool for breast cancer—has 87% sensitivity.

Cancer origin:📍The Galleri test can detect the location of cancer with 93.4% accuracy.

🌅 Early detection: During one study (PATHFINDER), approximately half of new cancer diagnoses using Galleri were stage I and II (early stage disease), writes The ASCO Post. 

Positive predictive value (PPV): Galleri has a PPV around 43%, based on results from PATHFINDER. This measures false-positives and “tell[s] you how worried someone with a positive test should be,” writes Spokane Regional Health.

• 43% PPV means that approximately 4 in 10 individuals with possible cancer detected (Galleri) will eventually get a confirmed cancer diagnosis, Galleri writes.

Negative predictive value (NPV): Galleri has a 98.5%. It’s highly likely that a negative cancer signal is accurate, and the user does not have any cancer.

Too good to be true?

While promising a way to fill an unmet need in cancer care, it may rest on some shaky grounds.

Low overall sensitivity 👇: The test has an overall sensitivity of 27.5% for early-stage cancer (stage 1–2), and it does not offer consistent detection across cancer types, according to a recent Lancet report. Sensitivity of 50% or more is considered effective.

😧 Unnecessary stress and anxiety: False-positives can stir unnecessary anxiety that can lead to additional adverse health outcomes and lower health span. And it might spur people to get unnecessary surgeries or procedures, which can be harmful.

No FDA approval: MCED (multi-cancer early detection) tests are not FDA-approved, which means the government has not determined it safe or effective, according to Cancer Therapy Advisor. By default, this increases its risk.

Misleading promotion: Most MCED-related social media posts have promotional tones and communicate misleading information about the test, according to a recent study. 📣

This can invalidate the test’s credibility, and experts like study author Brooke Nickel, PhD, of the University of Sydney, claim the test is “unnecessary for most people” and has shaky evidence, in some cases.

Financial burden: The Galleri test costs just under $1,000. Experts recommend doing it annually, which can become a costly undertaking. Downstream costs from positive results can become extremely high as well.

Moreover, MCED research can cost “hundreds of millions or even billions of dollars,” says John B. Kisiel, MD, a gastroenterologist and professor at Mayo Clinic in Rochester, Minnesota, in Cancer Therapy Advisor.🫰

It does not diagnose cancer: Similar to other screening tools, it will require additional resources and tests to confirm/deny the presence of cancer.

Can MCEDs reduce the risk of death?

The Galleri test is NOT proven to lower risk of death, but evidence suggests that early detection increases the likelihood of survival, especially among lethal types of cancer.

↘️ For instance, stage I ovarian (ovaries only) has a cure rate of 90%. The 5-year survival rate of advanced disease drops to 30%.

Given there are no accurate ways to screen for ovarian cancer, Galleri may be a viable option that has secondary survival benefits. This may extend to other fatal cancers.

Put it all together

MCED tests like Galleri are limited, but it is a promising innovation in the quest for more early detection of cancer. Jody Hoyos, CEO of the Prevent Cancer Foundation, sums up its potential:

• Better treatment outcomes.

• More treatment options.

• Less intensive treatment.

• Increased lifespan.

Continue the conversation

YOUNG AND DIAGNOSED: Why is cancer increasing in young people?

GALLERI QUEST: U.S. providers can order the Galleri test to Quest Labs.

COLON CANCER? The risk is higher than you’d think.

Until next time,

Erin

_{The information provided about wellness items and beverages is for general informational and educational purposes only. We are not licensed medical professionals, and the content here should not be considered medical advice. Drug interactions may occur, so talk to a doctor before trying any of these suggestions.}

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