What should you know about liquid biopsy startups?

A liquid biopsy usually uses a blood sample to look for circulating tumour DNA or other signals released by cancer cells. A startup may focus on finding cancer earlier, identifying changes in an established tumour, matching treatment to molecular features, or monitoring how tumour material changes over time. These are different goals, so the same test type should not be assumed to answer every question.

A blood test may be easier to repeat than a procedure that removes tissue. It can still miss a tumour signal when the sample contains too little detectable material, and a detected signal does not by itself describe the whole tumour. Tissue may be needed to confirm a diagnosis, examine cells, or perform testing that blood cannot provide.

Ask what the test is designed to detect, whether it is being used for diagnosis, treatment selection, or monitoring, and how the result will change the next decision. Check whether a positive result requires confirmation and what a negative result does not rule out. Discuss the test with the oncology team, especially if you are considering a commercial test outside your usual care.

Keep the laboratory report and ask which sample was analysed, when it was collected, and whether the result is actionable for your cancer type. Read more about [Circulating Tumour DNA Testing](/technology/circulating-tumour-dna-testing/) and [Biopsy](/treatments/diagnostics-and-staging/biopsy/).

Contact your cancer team promptly if a result is described as urgent, if you are told it may indicate a treatment change, or if you have new symptoms while waiting for interpretation. Seek emergency help for severe breathlessness, chest pain, fainting, confusion, or bleeding that does not stop. The test result should not delay care for new or worsening symptoms.

What question is this test intended to answer? Could tissue testing give information the blood sample cannot? How will a positive, negative, or inconclusive result affect my next step? Does the result need confirmation before treatment changes?