For those who are not familiar with memes, the term is defined in the following way in the Wikipedia:
...[A]n Internet meme is...an idea that is [often] propagated through the Web. This idea may take the form of a hyperlink, video, website, hashtag, or even just a word or phrase. This meme may spread from person to person via social networks, blogs, direct email, news sources, and other web-based services. An Internet meme may stay the same or may evolve over time, by chance or through commentary, imitations, parody, or even by collecting news accounts about itself.
For me, the term liquid biopsy qualifies as a meme. I first came across it on the web in mid-October last year and posted a blog note about its use on October 20th (see: (see: Does the New Term "Liquid Biopsy" Make Any Sense?). I Googled the term today and got almost 100,000 hits. My initial understanding of the term, as expressed in this earlier note, was that it referred to the detection of the HER2 antigen in serum, presumably released by circulating tumor cells (CTCs).
Unfortunately and perhaps predictably for a meme, the definition seems to be shifting. Only a few days ago, researchers at Massachusetts General Hospital revealed a chip for isolating CTCs from the blood (see: Johnson & Johnson "Liquid Biopsy" Cancer Blood Test: What It Would Mean for Patients). The lead investigator for the device had this to say about it:
"This is like a liquid biopsy" that avoids painful tissue sampling and may give a better way to monitor patients than periodic imaging scans, said Dr. Daniel Haber, chief of Massachusetts General Hospital's cancer center and one of the test's inventors.
It's rather easy to develop a theory why the term biopsy resonates with both patients and medical writers. It connotes a degree of certainty about a diagnosis, due in large measure to the success of pathologists in diagnosing lesions using small tissue samples. This may explain, in part, the rapid adoption of the notion of the liquid biopsy. However, I am not confident that it will continue to be associated only with the detection of CTCs or their antigen products in the serum. It could morph to some broader use such as the presence of tumor serum biomarkers absent the documented presence of CTCs.
To add some historical perspective to this blog entry, the term "liquid biopsy" dates back to an informal discussion at Harvard's Center for Engineering in Medicine, back in thε fall of 2004, where Mehmet Toner, Ron Tompkins and I were discussing the implications of being able to detect as few as 1 malignant cell in 10^12 events in peripheral blood. It was Mehmet, in fact, who coined the term "Liquid Biopsy" at that time. This investigative effort progressed, with very consistent returns on identifying circulating malignant epithelial cells being possible by 2006, as we hoped that we would be able to demonstrate. We ultimately reported our findings in Nature in December of 2007. Since that time, continued exploration of the topic of CTCs has demonstrated that this cell contingent is a very real component of the pathogenesis of malignant neoplasms. Thus, they represent an ideal target for further investigation, in terms of CTCs being suitable as an early warning surrogate for both primary presentation of disease as well as identifying recurrence in the setting of patients in clinical remission.
Posted by: Ulysses J. Balis, M.D. | January 08, 2011 at 08:44 AM