“Doctor, I saw an ad for that Galleri test that can detect 50 different cancers with just a blood draw. Should I get it?”

I hear this question almost daily now. Between online ads, social media posts, and well-meaning friends sharing articles, my patients are bombarded with information about multi-cancer early detection (MCED) tests. The marketing makes it sound like a no-brainer, but the medical reality is more complicated.

What These Tests Actually Do (and Don’t Do)

MCED tests like Galleri analyze your blood for tiny DNA fragments that cancer cells shed into your bloodstream. I like to think of it as looking for molecular breadcrumbs that tumors leave behind. When the test finds something suspicious, it tries to predict not just that cancer might be present, but where in your body it might be located.

Here’s what “early detection” actually means in this context, and it might surprise you. These tests don’t typically catch stage 1 cancers. The current Galleri test, for example, detects only about 28% of early-stage cancers (stages 1-2). What they’re better at finding are more advanced cancers that shed more DNA into the bloodstream.

This is quite different from the ctDNA monitoring I’ve written about before. That technology works well for tracking known cancers during treatment. These screening tests are trying to find cancer in people who feel perfectly healthy, which is a much harder task.

The Numbers You Need to Know

In the latest clinical trials, about half of people who get a positive MCED test result turn out not to have cancer after further testing. That’s roughly a 50% false positive rate.

Think about what that means for your life. You get a call saying “we found a cancer signal,” then spend weeks or months getting scans, biopsies, and specialist visits, only to learn it was a false alarm. The psychological impact can be substantial. I’ve had patients describe those weeks as among the most stressful of their lives.

False negatives happen too. The test might miss a cancer that’s actually there, giving you false reassurance. This is why these tests should never replace standard screening like mammograms, colonoscopies, or Pap smears.

Who Might Benefit vs. Who Should Wait

I would consider MCED testing most seriously for patients at higher risk. This might include people with strong family histories of multiple cancers, those with genetic predispositions, or individuals already getting intensive screening for other reasons.

For average-risk people, especially those under 50, I usually suggest waiting. If you’re not up to date on your standard screenings, focus there first. A mammogram, colonoscopy, prostate evaluation, cervical cancer screening and even a skin check have proven benefits. These MCED tests are meant to supplement, not replace, established screening.

The Conversation to Have with Your Doctor

Before considering an MCED test, ask yourself some key questions. Are you prepared for the possibility of additional testing if the result is positive? Can you afford not just the initial test (often $1000 or more out-of-pocket) but potentially expensive follow-up imaging and procedures?

Most insurance doesn’t cover these tests yet because they are not FDA-approved. The testing happens under laboratory regulations that focus on technical accuracy, not clinical outcomes.

Also consider whether you’re the kind of person who would follow through with additional testing. If you’re not willing or able to pursue further evaluation after a positive result, MCED testing probably isn’t right for you.

What’s Coming Down the Road

It is exciting that the technology is quickly improving. Researchers are working on tests that are more likely to find an early-stage cancer and more accurately identify where it is located. Large clinical trials are underway to see if these tests actually save lives, not just detect cancer earlier.

Within the next few years, we should have much clearer evidence about who benefits most and when these tests should be used. The FDA is reviewing applications for approval, which could lead to insurance coverage and clearer guidelines.

I’m optimistic about MCED testing’s potential, but right now we’re in a period where the promise exceeds the proven benefit. For most people, the best approach is staying current with proven screenings while keeping an eye on how this field develops.

The decision comes down to your own personal risk tolerance, financial situation, and peace of mind. Just make sure that you’re making that decision with clear information, not based on marketing hype.

Written By: Tiffany Troso, MD Medical Oncologist and Founder of Winning The Cancer Journey
http://www.linktr.ee/drtiffanytroso