Whole-body MRI and cancer blood tests

Only a handful of cancer screenings have been shown in large studies to save lives. They are matched to your age, sex, and risk, are covered by most insurance at no cost to you, and remain the foundation of cancer prevention.

• Breast cancer
• Cervical cancer
• Colorectal cancer
• Lung cancer (for people at high risk)
• Prostate cancer (a personal decision for some men)

No major medical society recommends whole-body MRI for healthy people at average risk. The only people who should get it for screening are those with certain rare inherited conditions (like Li-Fraumeni syndrome) that cause aggressive cancers early in life.

For everyone else:

• Unclear findings snowball. More scans, biopsies, worry, lost sleep, and bills. Sometimes surgery for something that was never dangerous.
• Many cancers it finds don’t need finding. Some are slow-growing and would never have hurt you. Others are already too advanced for early detection to help.
• No study has shown it helps healthy people live longer or better.
• A “clean” scan is not a clean bill of health. MRI can miss cancers, and it can’t tell you what will develop next year. People who feel reassured may ignore new symptoms or skip their proven screenings.

These blood tests look for traces of cancer DNA. The idea is exciting, and research is ongoing. But here is where things stand:

• No guideline recommends them, and they are not FDA-approved. An FDA advisory panel voted in favour of Galleri in September 2026; the FDA has not yet decided. Approval would mean the test does what it claims — not that it saves lives. It usually costs close to $1,000 a year, out of pocket.
• A negative result does not mean you don’t have cancer. In the largest studies, the test caught only about 3 to 4 out of every 10 cancers diagnosed during the following year.
• Many positive results are false alarms. A positive result starts a search with scans and procedures, and there is no standard plan for what to do if nothing is found.
• The biggest trial did not meet its main goal. The NHS-Galleri trial in England randomly assigned more than 140,000 people to get the test or not. It did not reduce the number of cancers found at a late stage (stage III or IV) — the main thing it was designed to show. It did find somewhat fewer stage IV cancers, a hopeful sign that still needs confirming. Whether the test saves lives is unknown.
• It is worst at the cancers screening is meant to catch early. These tests are much better at finding advanced cancers than early ones.

The biggest risk isn’t the blood draw or the MRI. It’s the false sense of security. A woman with a “normal” whole-body MRI who skips her mammogram, or a 55-year-old with a negative Galleri who never does a colon cancer test, has swapped a test proven to save lives for one that isn’t.

A stool test for colon cancer (FIT) costs a small fraction of a whole-body MRI and can be done at home. It can find colon cancer early, and the colonoscopy that follows a positive result can find and remove polyps before they turn into cancer. A blood test can’t do that.

1. 1First, make sure every guideline-recommended screening for your age, sex, and risk is up to date.
2. 2Talk with your doctor before ordering, not after you get a result.
3. 3Ask: “If this test finds something unclear, what happens next, and who pays for it?”
4. 4Remember that a negative result changes nothing. Keep doing your regular screenings, and see your doctor for any new symptom.

Millions of Americans are behind on cancer screening. Many say cost is the reason: being uninsured, a copay for a follow-up test, unpaid time off work, or no ride to the appointment. Simple steps like mailing FIT kits to people’s homes and helping them through the follow-up are proven to get more people screened.

If you were planning to spend a few thousand dollars on an MRI or a yearly blood test that isn’t proven to help, that same money could pay for colon cancer tests, mammograms, or rides to follow-up appointments for people who would otherwise go without. That is how lives are saved.