What Is a Liquid Biopsy for Lung Cancer?

Mutation-Based Detection

Methylation-Based Detection

Biomarkers for Liquid Biopsies

• Circulating Tumor DNA (ctDNA) Tumor cells release DNA fragments into the bloodstream. When analyzing a liquid biopsy, laboratory technologists can recognize these fragments and reveal genetic mutations that give information on growing cancer.

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• Circulating Tumor Cells (CTCs) Intact cancer cells can detach from the main tumor into the bloodstream. CTCs found in a liquid biopsy can tell providers a lot about the tumor and how likely it is to spread.

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• Extracellular Vesicles (EVs) Tumor cells release these small particles, which hold protein, RNA, and DNA. These clues can help healthcare providers detect and monitor cancer growth.

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• Prognosis prediction: Higher CTCs in the blood can mean a worse prognosis. Frequent monitoring of CTCs can indicate how fast your cancer is spreading or improving.
• Treatment guidance: Liquid biopsy results can suggest what kinds of treatments may work best. For example, if a cancer cell has a certain DNA change that is the main driver of cancer growth, targeted therapy can attack that specific DNA change in order to shut down the specific pathway promoting cancer growth.
• Traditional biopsy replacement: If a patient is unable to have a more invasive traditional biopsy, a liquid biopsy may offer the same information, depending on the cancer.

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In research studies, experts have explored using other body fluids to perform liquid biopsies. These include:

• Cerebrospinal fluid: Gathered through a lumbar puncture (also known as a spinal tap), this body fluid may soon offer monitoring for lung cancer which has spread to the brain and nervous system.

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• Urine: Cancer biomarkers in urine could one day provide a lung cancer screening tool.

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• Saliva: New techniques show analysis of cancer biomarkers in saliva to determine lung cancer prognosis and guide treatment.

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• Pain after procedure
• Nerve injury from poor technique
• Hematoma — blood gathering from lack of pressure

These risks are uncommon and avoidable if the healthcare provider drawing the blood has been trained in proper technique.

“The amount of DNA in the blood might be dependent on the size of the tumor and the stage,” says Fred R. Hirsch, MD, PhD, the executive director of the center for thoracic oncology at the Mount Sinai Tisch Cancer Institute in New York City. “Sometimes there is not enough DNA for reliable examination. Sometimes there’s a discrepancy between the molecular findings in the blood and in the tumor.”

In the future, the role of liquid biopsies in treating lung cancer may expand. “I see a role for liquid biopsy in the treatment decisions for individual patients,” Hirsch says.

“I also see a future role in monitoring treatment effects and an early determination of when a tumor gets resistant to the given molecular therapy or immunotherapy,” he says. “A liquid biopsy may detect increasing abnormal tumor DNA in the bloodstream, indicating tumor progression, for instance, well before it can be seen on a CT scan.”

• Liquid biopsy, which can help doctors identify the mutations in a cancer without surgery or invasive procedures to obtain tumor tissue, may be particularly helpful for improving the diagnosis and treatment of lung cancer.
• Liquid biopsies can help identify a tumor’s genetic mutations, which can help patients get more pinpointed therapy and improve prognosis.
• Liquid biopsy has some limitations, but continuing research and development will likely expand its role in diagnosing and treating lung and other cancers.