The Plasma Solution for a Biopsy-Free Lung Cancer Diagnosis
Written by Daphne Crum
Edited by Minjae Yoo
Jan 23rd 2022
Edited by Minjae Yoo
Jan 23rd 2022
An individual exhibits signs of non-small cell lung cancer, a rapidly progressive illness. Their oncologist wants to confirm a diagnosis as soon as possible, but asking the patient to undergo a biopsy to run tests is a tall order. If only physicians could provide an alternative test for lung cancer that was less invasive and just as accurate, if not better, than a tissue biopsy.
A recent study brings attention to a new method of testing plasma for cancer instead! Plasma is the liquid component of the blood made up of water, proteins and other materials that help the body to fight infections, remove waste and regulate other functions. Over 50% of our blood is composed of plasma, and if DNA remnants from cancerous tumors could be identified floating around in our plasma with a simple blood draw, scientists could potentially genotype and confirm a positive non-small cell lung cancer diagnosis in patients without ever needing surgery.
How would our plasma be able to tell us anything like this? Researchers could use a droplet digital polymerase chain reaction assay, in which small fragments of cancerous tumor DNA are identified within individual drops of plasma and then cloned for further analysis (Sacher et al., 2016). After separating the patient’s plasma from their blood, tags that code for DNA fragments associated with lung cancer are added to the genetic material in the plasma. The tags that find genetic matches glow to indicate the presence of a cancerous mutation. This glowing signal is made easier to identify by copying the genetic material many times to make the glow brighter.
The patients in this study were individuals with “non-squamous” lung cancer, meaning their cancers were known to be caused by one identified genetic mutation. Specifically, these patients had mutations in EGFR and KRAS receptor proteins responsible for signaling cell growth. These mutations cause unnecessary continuous signaling and cancerous cell division. Each patient in the study underwent a biopsy to have lung tissue-genotyping as a baseline to compare to the new plasma analysis technique. The total time it took to complete the test and receive results for the plasma analysis took an average of 3-7 days, while the biopsy analysis results took anywhere between 12-27 days. Additionally, plasma genotyping was 64-82% as accurate as the biopsy when it came to identifying the correct mutations at the cause of each cancer case (Sacher et al., 2016)!
Significant research has since been conducted, including a newer study with twice the number of patients undergoing similar plasma analysis trials. This study ultimately confirmed that plasma testing was 35.8% more accurate than biopsies when it came to targeting and identifying cancerous mutations (Aggarwal et al., 2018). This research emphasizes the implications of further developing a faster, less-invasive path of testing to diagnose non-small cell lung cancer. Pinpointing the root-cause of cancerous mutations with plasma tests could lead health-care professionals to prescribe more effective, personalized courses of treatment to fight cancer than ever before!
References
Aggarwal C., Thompson J. C., Black T. A., et al. (2018). Clinical Implications of Plasma-Based
Genotyping With the Delivery of Personalized Therapy in Metastatic Non–Small Cell
Lung Cancer. JAMA Oncology. 5(2), 173-180. https://doi:10.1001/jamaoncol.2018.4305
Sacher A. G., Paweletz C., Dahlberg S. E., Alden R. S., O’Connell A., Feeney N., Mach S. L., Jänne P. A., Oxnard G. R. (2016). Prospective Validation of Rapid Plasma Genotyping for the Detection of EGFR and KRAS Mutations in Advanced Lung Cancer. JAMA Oncology, 2(8), 1014-1022. https://doi.org/10.1001/jamaoncol.2016.0173