Early cancer detection from routine blood tubes: closer than we thought
Early cancer detection through a blood test — the so-called liquid biopsy — is one of the most promising developments in preventive medicine.
A liquid biopsy searches for cell-free DNA in the blood — small fragments of genetic material released when cells die. Tumor cells shed more DNA than healthy cells, and that tumor DNA carries characteristic mutations. If you can detect it in a blood sample, you can in theory identify cancer long before a lump is palpable or a tumor visible on imaging.
The problem with the right tubes
Most liquid biopsy research uses specially designed blood collection tubes — EDTA tubes or so-called Streck tubes — that stabilize cell-free DNA during processing. These tubes are more expensive, require specific handling, and are not universally available. In routine hospital practice, blood for biochemical analysis is drawn into heparin separator tubes. The residual plasma from those tubes is normally discarded.
The eLife study investigated whether that residual plasma could be used for cell-free DNA analysis. Healthy volunteers donated blood simultaneously into multiple tube types, and DNA quality and quantity were compared. The result: heparin residual plasma yielded comparable amounts and quality of cell-free DNA as the specialized tubes, provided processing occurred within a reasonable time window.
From research protocol to hospital practice
The implications are considerable. Hospitals process thousands of blood tubes daily for routine laboratory testing. If residual plasma from those tubes can be repurposed for DNA analysis, early cancer detection would require no extra blood draw, no special tubes, and no additional logistical burden. It could make liquid biopsies substantially more accessible — including in hospitals with limited resources.
That is the theory. Practice requires further validation: larger cohorts, patients with confirmed tumors, and comparison against standard imaging and tissue biopsies. Guidelines for how long residual plasma remains usable, and how processing should be standardized, are still lacking. But the evidence is shifting: the barrier to liquid biopsy may not need to be as high as previously assumed.