by Krista Toomre, MD
Family Medicine
Boulder Medical Center
Early cancer detection saves lives, but most routine screenings only test for a handful of cancers. The Galleri® test is a multi-cancer early detection (MCED) blood test that can spot DNA signals from more than 50 types of cancer in the bloodstream—even before symptoms appear.
Unlike conventional screenings (such as mammograms or colonoscopies), Galleri analyzes cell-free DNA (cfDNA) to identify abnormal methylation patterns. These patterns act like a fingerprint, helping to determine whether cancer is likely present and, in many cases, where in the body it may have originated.
It’s important to note: Galleri is meant to complement, not replace, standard cancer screenings.
Why Providers May Recommend the Galleri Test
- Expanded detection: Galleri can identify cancers for which no established screening method exists, including pancreatic, ovarian, and liver cancers.
- Early-stage insights: Studies suggest adding Galleri to traditional screenings can nearly double the number of cancers detected.
- High specificity: The test’s reported false-positive rate is about 0.5%, which is considered low compared to many screenings.
The Galleri gives us another tool for identifying cancers earlier, sometimes before symptoms begin. While it doesn’t replace mammograms, colonoscopies, or other proven screenings, it may provide additional peace of mind for patients at higher risk.
Limitations and Considerations
While promising, Galleri also comes with important caveats:
- Stage sensitivity varies: Detection rates are lower in early stages—about 17% for Stage I and 40–50% for Stage II cancers. Sensitivity increases for later stages, reaching about 90% for Stage IV.
- False positives: Some positive results may not actually indicate cancer. Follow-up imaging and tests are usually required. A repeat test at six months is currently offered at no cost.
- Cost and insurance: The list price is around $949; most insurance providers do not yet cover the test.
Final Takeaway
The Galleri test represents a significant step forward in multi-cancer early detection, offering hope for earlier diagnosis of cancers without standard screening options. However, it’s not a substitute for routine cancer screenings, and its effectiveness varies by cancer type and stage.