Liquid Biopsy: Are We Ready?
Keith Kaplan, MD, Chief Medical Officer
Liquid biopsy is defined as, “A test done on a sample of blood to look for cancer cells from a tumor that are circulating in the blood or for pieces of DNA from tumor cells that are in the blood. A liquid biopsy may be used to help find cancer at an early stage. It may also be used to help plan treatment or to find out how well treatment is working or if cancer has come back. Being able to take multiple samples of blood over time may also help doctors understand what kind of molecular changes are taking place in a tumor.”*
Often times the test is regarded as “non-invasive” as it can be performed with simple venipuncture specimens or voided urine samples.
These tests are gaining traction within the industry as a viable alternative to traditional screening methods for cancer. Study results are turning up positive data in favor of the tests, and a recent report by financial services firm Cowen & Co. said annual sales for the tools could surpass $10 billion.
So, liquid biopsy provides a non-invasive way to diagnose, monitor and treat cancer with less radiology and potentially less “pathology” in terms of conventional tissue diagnostics.
The technology has the potential to provide information about cancers without invasive biopsies using circulating biomarkers. These biomarkers include proteins, RNA and DNA, and can be used in initial detection, diagnosis, monitoring and detection of recurrence. While protein-based tumor markers have been used in routine pathology for many years, the ability to detect mutations in circulating DNA is relatively new and poised to enter clinical practice.
Still, a number of issues remain, and it is important that such markers are fully validated before they enter clinical practice. Although evidence of clinical utility and cost effectiveness are major hurdles, it is likely that the use of liquid biopsy in defined settings could substantially benefit cancer patients.
Using liquid biopsy we can offer less invasive and less risky means to make a diagnosis than with biopsy. The test can be performed during treatment and perhaps mitigate issues with tumor heterogeneity in tissue samples alone.
This is all good news. Unless you are a biopsy. Then it could mean fewer of you. And fewer biopsies for pathologists to read will bring drastic changes to our field. It will change the way we screen, diagnose, treat, monitor and respond to drug-resistance in a dramatic fashion.
There are over 22,000 PubMed results for “liquid biopsy” with over 1,200 results for “liquid biopsy review.” It is an active area of research and investment in a race to market new tests for safe and effective patient management in oncology.
Folks with names like Bezos and Gates are investing hundreds of millions of dollars to make these tests a reality. I, along with others practicing today, will implement this technology in our laboratories. We will shift from the tissue biopsy business to the liquid biopsy business.
How far will this technology take us to detect incipient tumors? Will it be used in tumors that have evaded this kind of testing in the past?
I think the sky is the limit. Cancer patients may no longer have to endure long sessions in an imaging center, infusion center or radiation therapy department.
They say medicine is the only business trying to constantly put itself out of business. Liquid biopsies will not put pathology out of business, but they will change our business.
For the better.
Tissue biopsies, forceps, lumpectomies, large resections, post-treatment resections, paraffin blocks, glass slides, immunohistochemistry,
I’m ready, and I suspect you’ll be ready, too!