Is liquid biopsy done with circulating tumour DNA testing?

A liquid biopsy is a sample-based approach that usually uses blood rather than a tissue specimen. Circulating tumour DNA testing examines small fragments of DNA released by tumour cells into the bloodstream. The laboratory analyses the sample for genetic changes or other tumour signals that may help the clinical team understand a cancer.

This test does not replace every tissue biopsy. The usefulness of the result depends on the cancer, the amount of tumour DNA present, and the question the team is trying to answer. A result that does not find a change may mean the blood sample did not contain enough detectable DNA; it does not by itself rule out cancer.

Ask what the test is intended to clarify, whether you need any preparation, and when the result may guide a treatment decision. Share your current medicines and recent cancer reports with the team. When results return, ask which finding is actionable, whether another sample is needed, and how the result fits with scans, examination, or tissue pathology.

Seek urgent medical help for heavy bleeding that does not stop, fainting, severe breathlessness, or chest pain after any blood draw. For ordinary bruising or soreness, contact the service if it becomes increasingly painful, swollen, red, or warm. Questions about the meaning of a result should go to the oncology team rather than being interpreted alone.

Ask whether this is a circulating tumour DNA test, what alteration or marker is being sought, and whether the result could change your treatment. Ask how a negative or inconclusive result will be followed up and whether tissue testing remains necessary.