What should you know about FDA-approved liquid biopsy?

A liquid biopsy uses blood to look for material released by tumours, such as fragments of circulating tumour DNA. The laboratory may examine genetic changes or other signals to help identify a treatment option, monitor a known cancer, or clarify whether a target is present.

A result can be positive, negative, or unable to provide a usable finding. A negative result may mean that the blood sample did not contain enough detectable material; it does not automatically rule out a tumour or a change that the test was not designed to detect. A tissue biopsy may still be needed to establish diagnosis or resolve uncertainty.

Ask what the test was approved to answer, which alteration or marker was assessed, and whether the result changes treatment. Confirm whether the sample was adequate and whether a tissue biopsy remains recommended. Keep the report and ask how the finding will be checked against imaging, pathology, and your symptoms.

Tell your clinician about previous cancer treatments and any relevant family or personal history. Do not start, stop, or change cancer treatment based on a blood result without the treating team’s interpretation.

The blood draw itself usually needs only routine observation, but seek urgent help for heavy bleeding that does not settle, fainting, severe dizziness, chest pain, or breathing difficulty. During cancer care, report new severe pain, confusion, fever, or rapid deterioration promptly, whether or not a liquid biopsy is pending.

What is this test intended to detect? What does a negative or inconclusive result mean? Is tissue sampling still needed? How could the result affect treatment or follow-up, and when will it be reviewed?