Liquid biopsy & multi-cancer early detection
Looking for traces of tumour DNA in a blood sample.

How it works
Tumours shed fragments of DNA into the bloodstream. Sequencing and machine-learning methods look for patterns — mutations or chemical marks such as methylation — that suggest a cancer and where it may be.
Why it matters
Some liquid biopsies already help guide treatment for diagnosed cancers; multi-cancer early detection tests aim to find cancers before symptoms.
Limits & open questions
Screening tests must show they reduce deaths, not just find more cancers. False positives, missed early cancers and overdiagnosis are real concerns, and regulatory reviews are ongoing.


