Here is a fact that surprises almost every patient who hears it. Cancerguard’s own labeling states that the test is not indicated for breast or prostate cancer screening. Those are the two most frequently diagnosed cancers in the United States.
The American Cancer Society projects 321,910 new breast cancer cases and 333,830 new prostate cancer cases in 2026, out of roughly 2,114,850 total new cancer diagnoses. That works out to about 31% of all new cancer diagnoses in the country — roughly three in ten — sitting outside what the test is designed to look for.
We want to be careful about how this lands, because it is easy to read it as criticism, and it is not. This is not a flaw in the test. It is what the test is for. The manufacturer says so plainly in its own materials. But there is a gap between what the labeling says and what people hear, and the phrase “cancer blood test” does a lot of quiet work in that gap. A patient who gives a tube of blood, receives a clean result, and walks away believing they have been screened for cancer is working from a picture that does not match the product. Nobody is lying to them. Nobody is telling them either.
Why these tests leave breast and prostate out
There are two reasons, and both of them are sensible.
The first is that breast and prostate cancer already have established screening pathways. Mammography has decades of evidence behind it. PSA testing, used thoughtfully and discussed with a physician, has a defined role. Multi-cancer early detection tests were built to address the opposite problem — cancers of the pancreas, ovary, esophagus, stomach and liver, which have no routine screening at all and are often found late. Designing a test around the gap rather than around the cancers already covered is a reasonable choice.
The second reason has to do with the biology of the signal itself. These tests look for fragments of tumor DNA and related markers circulating in the bloodstream. How much of that material a tumor releases varies a great deal by cancer type, and early-stage breast and prostate tumors generally shed relatively little of it. Prostate cancer in particular is often slow-growing, and some of it would never cause harm in a person’s lifetime — so a test that flagged it aggressively would risk creating anxiety and follow-up procedures without a clear benefit. Building the panel around cancers that shed a stronger signal and carry a heavier mortality burden is a defensible design decision.
Galleri takes a similar position from a different angle. GRAIL states explicitly that Galleri is to be used in addition to, not instead of, mammography, colonoscopy, PSA testing and cervical screening. The published figures show why that matters: in PATHFINDER 2, episode sensitivity was 69.8% for the twelve cancers responsible for roughly two-thirds of US cancer deaths — but 39.3% across all cancers. Both numbers are real. Only one of them tends to get quoted.
Cancerguard’s development studies reported 68% sensitivity across six of the deadliest cancers and 64% overall sensitivity when breast and prostate cancers were excluded, with specificity of 97.4%. Neither test is FDA-approved; both are offered as laboratory-developed tests and are generally not covered by insurance. We cover the details in our guide to what the Cancerguard test actually looks for.
What this means for a real person
Consider a 55-year-old woman who takes a multi-cancer blood test, gets a result showing no cancer signal detected, and feels reassured. That reassurance is reasonable as far as it goes. But the single most likely cancer she will face in her lifetime was never in scope. If that clean result nudges her to postpone a mammogram, the test has quietly made her screening worse rather than better.
The same holds for a 60-year-old man and prostate cancer, which accounts for close to three in ten of all new cancer diagnoses in American men. For women, breast cancer accounts for roughly a third of new diagnoses. These are not edge cases. They are the center of the distribution.
None of this is an argument against blood testing. It is an argument for knowing what you bought.
What actually screens for breast cancer well
Before the evidence below: everything in this section describes dedicated breast MRI, a different exam from the whole-body screening scan we perform. The numbers here do not transfer to a whole-body protocol.
Mammography remains the foundation, and nothing here replaces it. But for women with dense breast tissue, where mammography is less able to see clearly, the MRI evidence is genuinely strong.
In the EA1141 trial published in JAMA in 2020, 1,444 women at average risk with dense breasts each received both an abbreviated breast MRI and digital breast tomosynthesis. Abbreviated MRI detected invasive cancer in 11.8 per 1,000 women, compared with 4.8 per 1,000 for tomosynthesis. Sensitivity for invasive cancer and DCIS combined was 95.7% for MRI versus 39.1% for tomosynthesis. MRI found all 17 invasive cancers in the study. Tomosynthesis found 7 of them.
The DENSE trial, published in the New England Journal of Medicine in 2019, randomized roughly 40,000 women aged 50 to 75 with extremely dense breasts. Supplemental MRI cut the interval-cancer rate — cancers appearing between scheduled screenings — from 5.0 to 2.5 per 1,000 screenings, with an MRI cancer detection rate of 16.5 per 1,000.
There is a trade-off, and it should be stated rather than skipped. MRI buys that sensitivity by giving up specificity: 86.7% versus 97.4% for tomosynthesis in EA1141, and the positive predictive value of biopsy was lower for MRI, 19.6% versus 31.0%. More cancers found, and more false alarms along the way.
The American Cancer Society recommends annual MRI alongside mammography for women with a lifetime risk of roughly 20–25% or higher, typically starting at age 30. It recommends against MRI screening for women below 15% lifetime risk, and makes no recommendation in the 15–20% range.
What actually screens for prostate cancer well
The same caution applies here: this is dedicated multiparametric prostate MRI, ordered by a physician after a PSA result. It is not what a whole-body screening scan is.
The pathway here starts with PSA testing and a conversation with your physician. MRI enters afterward, and its role is specific.
In the PRECISION trial published in the New England Journal of Medicine in 2018, 500 men were assigned either to MRI-targeted biopsy or standard TRUS-guided biopsy. The MRI-first pathway detected clinically significant cancer in 38% of men versus 26% with standard biopsy, and clinically insignificant cancer in only 9% versus 22%. More of what matters, less of what does not.
Guidelines reflect this with real differences in emphasis. The European Association of Urology and the NCCN recommend multiparametric MRI before an initial biopsy with a “strong” designation, while the AUA and SUO state that mpMRI “may” be used — a meaningful distinction if you are comparing advice from different sources.
One point deserves to be stated without softening: the EAU’s 2026 guideline carries a strong recommendation not to use MRI as an initial screening tool in asymptomatic men. MRI is how a biopsy decision gets made after a PSA result raises a question. It is not the front door. Our overview of the five most common cancers in men walks through where prostate screening fits alongside the rest.
The part we will not let you misread
Everything in the two sections above describes dedicated breast and prostate MRI — and that is not what a whole-body screening scan is.
The breast MRI evidence comes from prone, contrast-enhanced breast protocols using positioning and sequences built specifically for breast tissue. The prostate MRI evidence comes from diagnostic multiparametric protocols with the full PI-RADS sequence set. A supine, non-contrast whole-body survey scan includes neither. Those detection rates do not transfer to it, and we would be misleading you if we suggested otherwise.
So to be explicit: a whole-body MRI is not a breast cancer screening test and is not a prostate cancer screening test. It does not replace a mammogram, a PSA discussion, a colonoscopy, or a dedicated breast or prostate MRI ordered by your physician. It is also worth knowing that published whole-body MRI screening studies in people without symptoms report confirmed cancer in a small minority of those scanned — roughly 1.57% across a 2025 European Radiology meta-analysis of 9,024 participants — while incidental findings are common. Both of those facts belong in your decision before booking, not after. And there is no published evidence yet that whole-body MRI screening extends life — that research does not exist for any screening MRI protocol or any MCED test.
Building a screening plan that actually covers you
The useful takeaway is not that one test is better than another. It is that coverage is something you assemble deliberately.
Start with the guideline-based screening that applies to you: mammography, cervical screening, colonoscopy, a PSA conversation, and low-dose CT if you have a smoking history. Add supplemental breast MRI if your risk profile or breast density supports it, which is a conversation for you and your physician. From there, understand what any additional tool adds — a multi-cancer blood test may extend coverage toward cancers with no routine screening, and whole-body imaging offers something different again: a structural look at your internal organs and a personal baseline for future comparison. Our comparison of cancer blood tests and whole-body MRI goes deeper on how the two approaches relate.
What none of them do is cover everything, and any test that seems to promise that deserves a second read of its own labeling.
If you are trying to work out where the gaps in your own plan are, that is a reasonable thing to talk through rather than sort out alone. Our team, including Medical Director Dr. Edward Tavel and our board-certified radiologists, is glad to help you understand what a scan can and cannot tell you before you decide anything.
Frequently asked questions
Which cancers is Cancerguard not designed to find?
Its labeling states it is not indicated for breast cancer screening, prostate cancer screening, or the detection of pre-cancerous lesions. What it is designed to detect is signals associated with a range of cancers, with emphasis on cancers that have no routine screening and high mortality. It is available to adults aged 50 to 84 with no cancer diagnosis in the past three years, and it is a laboratory-developed test rather than an FDA-approved one.
Does Cancerguard test for breast cancer?
No. Cancerguard is not indicated for breast cancer screening. Mammography remains the recommended screening test, with supplemental MRI for women whose risk level or breast density supports it, as discussed with their physician.
Does Cancerguard test for prostate cancer?
No. Cancerguard is not indicated for prostate cancer screening. The established pathway begins with a PSA discussion with your doctor, with multiparametric MRI used afterward to help decide whether a biopsy is needed.
What cancers do blood tests miss?
No multi-cancer blood test covers every cancer type. Beyond breast and prostate, sensitivity varies widely by cancer type and stage — Galleri's PATHFINDER 2 reported 69.8% episode sensitivity for the twelve cancers causing about two-thirds of US cancer deaths, but 39.3% across all cancers. A negative result does not rule cancer out.
Can a whole-body MRI screen my breasts or prostate?
No. A whole-body MRI is a supine, non-contrast survey scan. It is not a dedicated prone contrast-enhanced breast MRI or a diagnostic multiparametric prostate MRI, and the detection rates published for those exams do not apply to a whole-body protocol.
Sources
- Cancer statistics, 2026
- Cancerguard® Multi-Cancer Early Detection Test
- Frequently Asked Questions (FAQs) for Patients
- Frequently Asked Questions (FAQs) for Providers
- GRAIL Presents PATHFINDER 2 Results of More Than 35,000 Participants Showing the Galleri® Test Substantially Increased Cancer Detection With Robust Performance and Favorable Safety at 2026 ASCO Annual Meeting
- Comparison of Abbreviated Breast MRI vs Digital Breast Tomosynthesis for Breast Cancer Detection Among Women With Dense Breasts Undergoing Screening
- Supplemental MRI Screening for Women with Extremely Dense Breast Tissue
- American Cancer Society Recommendations for the Early Detection of Breast Cancer
- MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis
- EAU Guidelines on Prostate Cancer
- NCCN Guidelines: Prostate Cancer Early Detection (Version 2.2025)
- Early Detection of Prostate Cancer: AUA/SUO Guideline (2026)
- Whole-body MRI for opportunistic cancer detection in asymptomatic individuals: a systematic review and meta-analysis
