DETECT-A: a blood test plus PET-CT found treatable cancers in 10,000 women with no symptoms
The first prospective interventional study of a multi-analyte blood test (CancerSEEK) in asymptomatic people: 26 cancers were first detected by the blood test, most of them localised, and the test roughly doubled the number of cancers caught by standard screening.
Overview
DETECT-A enrolled 10,006 women aged 65-75 with no history of cancer in the Geisinger health system. A blood test measuring mutations in cell-free DNA and protein markers (CancerSEEK) was performed; a confirmed positive led to whole-body PET-CT, and imaging-positive participants were referred for diagnosis.
Twenty-six cancers were detected by the blood test, of which 17 were localised or regional and 12 were treated with surgery with intent to cure. Standard-of-care screening detected a further 24 cancers, so combining the blood test with existing screening roughly doubled detection (from about a quarter to about half of incident cancers). Fewer than 1% of participants had an unnecessary invasive procedure.
It proved that a blood-first screening pathway can be safely operationalised and that many blood-detected cancers are at a curable stage.
- Blood test alone detected 26 of 96 incident cancers (about 27% sensitivity); with standard screening the combined sensitivity was about 52%
- 17 of 26 blood-detected cancers were localised or regional; 12 patients had surgery with curative intent
- The blood test found cancers in organs with no standard screening (ovary, kidney, appendix, uterus, lymphoma)
- Participants did not reduce their uptake of standard screening after joining the study
A blood test can find early, treatable cancers in people who feel well, including cancers for which no screening exists. It is not a replacement for mammography or colonoscopy but a possible addition. Larger randomised trials are needed to show benefit outweighs harm.
- Single-arm, single health system, women only; no mortality endpoint
- Sensitivity of about a quarter for all incident cancers means most cancers were missed
- PET-CT confirmation for all positives is costly and exposes participants to radiation
- CancerSEEK's commercial successor tests differ in design, so performance does not transfer directly