The science underlying "liquid biopsies" is rapidly growing more sophisticated. There is even an upcoming conference devoted solely to this topic (see: Liquid Biopsy Summit). I posted my first note about liquid biopsies almost six years ago which was followed by others (see: Does the New Term "Liquid Biopsy" Make Any Sense?; Continuing Discussion about the "Liquid Biopsy"; Rapid Adoption of the Term "Liquid Biopsy" on the Web). The term originally referred to the isolation and analysis of circulating tumor cells (CTCs) but has now come to mean the analysis of circulating tumor molecules, DNA (ctDNA) and RNA (see: Circulating tumor DNA: A new generation of cancer biomarkers; New Liquid Biopsy Test Uses Platelet RNA as Cancer Diagnostic). Now comes news that Illumina is launching a company with the goal of detecting early stage, pre-symptomatic cancer by the analysis of cancer DNA in the blood (see: Illumina Creating Company to Develop Early-Stage Cancer Detection Test). Below is an excerpt from the article describing this initiative:
Illumina...[is] forming a company to attempt to develop such a test [for cancer screening]. The company, called Grail, has raised over $100 million, mostly from Illumina and the venture capital firm Arch Venture Partners, but also from Microsoft’s co-founder, Bill Gates, and Jeffrey P. Bezos, the founder and chief executive of Amazon.....But some experts said that developing ...a test [for ctDNA] would be a daunting task....The blood test, using intensive DNA sequencing, would look for patterns of telltale mutations. Many companies are developing similar tests, known as liquid biopsies, that use a blood sample to replace or supplement a conventional biopsy, in which a sample of the tumor is extracted from the body by needle or surgery. In just the last week, one company, Guardant Health, said it had raised nearly $100 million in its latest funding round while another, Exosome Diagnostics, said it had raised $60 million. But so far, liquid biopsies are mainly used for patients already known to have cancer. The tests help determine the particular mutations in the tumor to help select the best drugs to use. Or they are used to monitor whether treatment is effective or to check for a recurrence. Detecting early-stage cancer, although an eventual goal of many liquid biopsy companies, is considered more difficult. Many cells, not just cancerous ones, shed DNA into the bloodstream, and many noncancerous cells have mutations that are also found in tumors.
The term liquid biopsy is even less appropriate now that tumor DNA or RNA are being analyzed compared to circulating tumor cells. However, this is a quibble. The key point is that the care of cancer patients is changing from evaluating those with a cancer diagnosis to very early detection of cancer in asymptomatic patients. In short, we are now on the verge of effective screening tests for cancer. Link this idea with the current rapid advances in cancer immunotherapy in which the drugs harness a patient's own immune system to kill cancer cells. We may soon be encountering a scenario with patients being told that they have an early stage of cancer but that all they need to do is take some pills for a few months to correct the problem.
The implications of all of this for the field of surgical pathology is that it could easily become a niche specialty, reserved only for the most complicated cases. I think that this may cause pathology to be defined in a very different way. On the research side and speaking mainly from an informatics perspective, the field of computational pathology, championed early by Dr. Mike Becich, is exploding because it's so deeply involved in cancer genomics which is highly computational. On the applied and clinical side of pathology, cancer will increasingly become a molecular diagnosis rather that a microscopic one. This conclusion is supported by the fact that molecular pathology and its professional society, the Association for Molecular Pathology, are rapidly expanding. Moreover, the evolution of the liquid biopsy will not be the exclusive territory of pathologists -- a host of other researchers and clinicians are actively engaged in this research.