Liquid Biopsy

A liquid biopsy is a test that looks for traces of cancer in a body fluid, usually blood, instead of in a piece of tissue. It can detect tumor DNA (ctDNA), tumor cells or proteins shed into the bloodstream. In lung cancer it is widely used to find treatable mutations, but it cannot diagnose mesothelioma on its own.

Origin

Scientists showed decades ago that DNA from tumors circulates in the blood; the term liquid biopsy came into wide use in the 2010s, as sequencing became sensitive enough to measure it. U.S. regulators first approved a blood-based tumor mutation test, for lung cancer, in 2016.

Significance in Asbestos Context

For lung cancer, a blood test can sometimes find mutations such as EGFR or ALK that guide targeted treatment while tissue results are pending. Mesothelioma is different: these tumors shed relatively little DNA into the blood and have few targetable mutations, so liquid biopsy has a limited role and is mainly studied in research. Blood markers such as soluble mesothelin (SMRP) have been studied for years but are not accurate enough to diagnose or rule out mesothelioma. Pleural fluid drained from the chest is also a kind of liquid sample, and cytology on that fluid can suggest mesothelioma, though most experts want tissue to confirm it. For a claim, asbestos trusts and courts generally rely on a pathologist's diagnosis, not a blood test. A negative liquid biopsy does not mean there is no cancer.

Example Sentence

The liquid biopsy found an EGFR mutation in her blood, so her oncologist started targeted therapy for the lung cancer while the tissue results were confirmed.

Related Terms

ctDNA, Biopsy, Biomarker Testing, Soluble Mesothelin-Related Peptides (SMRP), Fluid Cytology, Tumor Marker, Non-Small Cell Lung Cancer, Pathology Report

Notes

• Ask what the test was looking for: a mutation to guide treatment, or signs of cancer itself.
• A normal result does not rule out cancer; tissue testing may still be needed.
• Keep the lab report; blood-based results are often filed separately from the pathology report.