Tempus liquid biopsy: what to know

Tumours can release small fragments of DNA into the bloodstream. A laboratory analyses a blood sample for selected genetic changes and may report findings that relate to targeted treatment, resistance, or clinical trial eligibility. The test does not usually show the tumour's location by itself, and a result must be interpreted alongside the diagnosis, scans, pathology, and treatment history.

A negative or uninformative blood result does not necessarily rule out a molecular change. There may not be enough tumour DNA in the sample, or the relevant change may not be covered by the test. A tissue [Biopsy](/treatments/diagnostics-and-staging/biopsy/) can sometimes provide a fuller sample when it is safe and appropriate.

Ask why the test is being recommended, what decision the result may inform, and whether tissue testing has already been done. Tell the team about previous treatments and bring available pathology and molecular reports. Confirm how the blood sample will be collected, where results will be reviewed, and when you should expect an explanation. Discuss whether a finding would change treatment now or simply provide information for a later decision. [Circulating Tumour DNA Testing](/technology/circulating-tumour-dna-testing/) explains the testing principle in more detail.

The blood draw itself usually involves brief needle-site discomfort, but contact the clinic for persistent bleeding, increasing swelling, severe pain, or signs of infection at the puncture site. Seek urgent care for symptoms of your cancer or treatment such as severe breathlessness, chest pain, confusion, sudden weakness, or uncontrolled bleeding. Do not wait for a liquid biopsy result when symptoms need immediate assessment.

Ask which molecular changes the test examines, whether the sample is adequate, how a negative result will be handled, and whether tissue testing is still needed. Ask how a detected change could affect treatment, what confirmation may be required, and who will explain the report in the context of your scans and pathology.