Exact Sciences liquid biopsy: what to know

A liquid biopsy uses a blood sample rather than removing a piece of tumour tissue. The laboratory may look for fragments of DNA released into the bloodstream, including changes that can help characterise a known cancer. This is related to Circulating Tumour DNA Testing.

The amount of tumour DNA in blood can vary, and a blood result may not reflect every area of a tumour. A result can therefore guide discussion without answering every diagnostic question. A tissue Biopsy may still be needed to confirm a diagnosis or provide information that blood cannot supply.

Ask why the test is being offered, what question it is intended to answer, and whether the sample is being used for diagnosis, treatment selection, or monitoring. Check how results will be explained and whether a tissue sample or another scan remains necessary.

Tell the team about current treatment and previous testing, because timing can affect how a result is understood. Ask which findings could change the care plan and what happens if the test is inconclusive. Do not change treatment from a report without discussing it with the prescribing team.

Liquid biopsy itself usually involves a blood draw, but seek help for persistent bleeding, marked swelling, fainting, or worsening redness at the needle site. Contact the oncology team promptly if new or worsening cancer symptoms appear; a planned blood test should not delay assessment of urgent symptoms.

What will this test look for? Could the result change my treatment? How reliable is the test for my cancer type and current situation? Would tissue biopsy add information, and when should I expect an explanation of the report?