A biopsy, which involves removing tissue from the body to test in a laboratory, is a vital part of cancer diagnosis and treatment. However, performing traditional biopsies for lung cancer can sometimes be difficult. Suspected or known tumor tissue can be difficult to access, and biopsy techniques may involve surgery, including anesthesia.

Liquid biopsies may be a major advance in cancer treatment and diagnosis. Instead of using tissue samples, liquid biopsies analyze body fluids (usually blood) to detect material shed by cancer cells. Applications of liquid biopsies include the detection, monitoring, and treatment of various types of cancer, including lung cancer.

1. Liquid Biopsies Find Cancer Evidence in the Blood

Liquid biopsies commonly test for two substances: circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). CTCs are actual tumor cells that have shed from their original source and are now traveling through the bloodstream. Circulating tumor DNA consists of DNA fragments released from these tumor cells. This ctDNA contains the mutations (genetic changes) specific to the cancerous tumor.

Next-generation sequencing is an advanced method used to examine and identify genetic mutations in cancer cells with high precision.

Other forms of liquid biopsy test for other biomarkers associated with cancer, such as cell-free DNA (cfDNA), RNA, extracellular vesicles (components of cellular communication), proteins, and antibodies. These biomarkers can offer insights into the presence and progression of cancer, as well as how well a person is responding to treatment.

2. Liquid Biopsies Are Noninvasive and Fast

Unlike traditional tissue biopsies, which require obtaining a sample of tumor tissue, liquid biopsies only require a quick blood draw. Once the blood is drawn, the sample is sent to a laboratory for testing.

The ease of performing liquid biopsies allows them to be conducted more frequently than traditional biopsies. This increased frequency helps in promptly detecting whether lung cancer is responding to treatment or spreading — or if it has returned after remission.

Additionally, liquid biopsy results are processed more quickly than traditional biopsy results, which means a person can more quickly start a new treatment option.

3. Liquid Biopsies Can Improve Lung Cancer Treatment

The DNA inside a tumor can change over time, leading to different genomic profiles within various parts of the tumor. A traditional biopsy, which samples only a specific part of the tumor, may provide an incomplete DNA picture. However, ctDNA found in a liquid biopsy can detect all variations in tumor DNA, which is especially important for individuals with multiple tumors.

Having a full DNA picture of your lung cancer is important because tumors containing certain genetic variations can be treated with specialized medication called targeted therapies. Liquid biopsies can help find special genetic variations that can match with an existing targeted therapy.

A study of more than 1,000 people who had liquid biopsies for their non-small cell lung cancer (NSCLC) found that the biopsies helped match people with cancer to targeted therapies — and those who received these targeted therapies lived longer. As research continues, both the number of tumor gene variations for NSCLC and the number of medications designed to target them are expected to grow quickly.

Additionally, liquid biopsies can be useful in tracking responses to other lung cancer treatments, such as immunotherapy. A study of 30 people found that the liquid biopsy process could detect response to the treatment as well as show warning signs in people who may experience side effects months later.

4. Liquid Biopsies Are Used for Metastatic Lung Cancer

Liquid biopsies are used in clinical practice for people with metastatic lung cancer (cancer that has spread). Because the cancer has spread throughout the body, cancer cells and DNA can be detected in the bloodstream. Liquid biopsies can be used to determine possible targeted therapy treatments and serve as a prognostic test, predicting the course of the disease.

Liquid biopsies are not currently used for lung cancer detection and lung cancer screening. A standard biopsy is still necessary for a first diagnosis of lung cancer because of the risk of false negatives and false positives (inaccurate test results).

If a doctor suspects lung cancer, they may order both a liquid biopsy along with a traditional biopsy to improve treatment. A study of more than 1,000 people found that those who had ordered liquid biopsies prediagnosis were more likely to get timely DNA profiling of their tumor and to receive treatment more quickly after diagnosis.

5. The FDA Has Approved Liquid Biopsies for Lung Cancer

Three liquid biopsies are approved by the U.S. Food and Drug Administration (FDA) for use in lung cancer treatment.

Guardant360 CDx detects four different types of gene mutation biomarkers that are seen in some types of lung cancer:

• EGFR exon 19 deletions, L858R, and T790M
• EGFR exon 20 insertions
• ERBB2/HER2 activating mutations
• KRAS G12C

FoundationOne Liquid CDx detects five different types:

• ALK rearrangements
• BRAF V600E
• EGFR exon 19 deletions and EGFR exon 21 L858R substitution
• MET single nucleotide variants and indels that lead to MET exon 14 skipping
• ROS1 fusions

Cobas EGFR Mutation Test v2 identifies mutations in exons 18, 19, 20, and 21 of the EGFR gene, including the T790M resistance mutation.

Learn more about the different types of lung cancer mutations and treatments that target them.

Talk With Others Who Understand

On MyLungCancerTeam, the social support network for people with lung cancer and their loved ones, more than 13,000 members come together to ask questions, give advice, and share their stories with others who understand.

Have you or a loved one had a liquid biopsy? Share your experiences in the comments below, or start a conversation by posting on your Activities page.