From the Research
The Galleri multi-cancer early detection blood test is a promising tool for cancer screening, but its effectiveness is limited by variable sensitivity across different cancer types and stages, and it should be used as a complement to established screening methods rather than a replacement. The test can detect signals for over 50 cancer types with a low false positive rate (less than 1%) and high specificity (99.5%), primarily by identifying cell-free DNA patterns associated with cancer 1. When cancer is detected, the test can predict the cancer's origin with 89% accuracy. However, its sensitivity varies significantly by cancer stage and type - detecting about 16% of stage I cancers, 40% of stage II, 77% of stage III, and 90% of stage IV cancers. The test performs better for certain cancers like liver and pancreatic cancer but worse for others like breast cancer.
Key Points to Consider
- The Galleri test has not yet demonstrated improved mortality outcomes in large randomized trials, such as the NHS-Galleri trial, which aims to establish whether a multi-cancer early detection test can reduce late-stage cancer incidence 1.
- The test costs approximately $950 and typically isn't covered by insurance.
- Patients should understand that a negative result doesn't guarantee absence of cancer, and positive results require follow-up diagnostic testing to confirm cancer presence.
- The test's effectiveness is still being studied, and more research is needed to fully understand its potential benefits and limitations, as discussed in a recent commentary on the promise of multicancer early detection 2.
Current Recommendations
- The Galleri test is recommended as a complement to established screening methods rather than a replacement.
- Patients should continue to follow established screening guidelines and discuss the potential benefits and limitations of the Galleri test with their healthcare provider.
- Further research is needed to fully understand the test's effectiveness and potential role in cancer screening, as highlighted by a recent study on patterns of mammography, Pap smear, and colorectal cancer screening services among women aged 45 and over 3.