What liquid biopsy is
Tumours release small fragments of DNA into the blood, called circulating tumour DNA (ctDNA). A liquid biopsy is a blood test that looks for these fragments and the genetic changes they carry.
What it is used for
- Choosing targeted treatment – in lung cancer, for example, it can identify mutations for which targeted drugs exist when a tissue biopsy is not possible or did not yield enough material.
- Monitoring response – falling or rising ctDNA can show how the disease is responding to treatment.
- Detecting resistance – new mutations can explain why a treatment has stopped working.
- Minimal residual disease – in trials and at some centres, the test is used to detect traces of disease after surgery.
Limitations
A negative result does not rule out cancer: some tumours shed very little DNA into the blood. That is why, in most situations, liquid biopsy complements a conventional biopsy rather than replacing it, and the initial diagnosis is still made from tissue.
Why it matters where it is done
Sequencing technology varies between laboratories, and interpreting the results takes experience. Centres with molecular tumour boards can say whether a mutation that is found actually changes treatment.
How we can help
We connect you with centres that use liquid biopsy in clinical practice, organise sample collection and transport, and translate the report so you can discuss it with your treating doctor.
Informational article. It does not replace medical advice; treatment decisions are made with your treating doctor.