A Liquid Revolution?

Liquid biopsy is now making its way into the clinic, but just how useful is it? In a bid to answer the question, the Association for Molecular Pathology decided to carry out its own literature review on the clinical utility of circulating tumor cells in cancer diagnosis (1). We spoke with first author Bert Gold, staff scientist at the National Cancer Institute, MD, USA, about what they discovered…

What prompted this review?

We realized the opportunity for further molecular characterization of cancers could be productive, both for the pathologist getting a better sense of what causes cancer, and for the treating clinician. The underlying aim is to try and treat all cancers in a more personalized way. The more we know about a tumor, the better we can choose the most appropriate therapy.

What were your key findings?

Firstly, we discovered that FDA-approved liquid biopsy methods already existed for breast cancer at the time we began our review. While the review was still underway, tests appeared for prostate and colon cancer as well, which shows that this technology has already proven its use in some cancers.

Liquid biopsy is noninvasive compared with scanning and surgical biopsy. It allows clinicians to monitor patients. It also has the potential – much like what was discovered with viral burden in HIV cases – not only to give us information on prognosis, but to provide further insight into the workings of cancer, and how best to treat it.

However, we also found that in the US, third party payers are often unwilling to reimburse the use of liquid biopsy methods. It is often the case that innovative diagnostics are spurred on by third party payers’ willingness to pay, but if no one pays, you can’t do the test. This makes it much more difficult to figure out how to best utilize technologies – not everyone has the funds for large clinical studies.

How will liquid biopsy impact diagnostics?

It could be revolutionary. Examining the genetic information from tumor DNA just by doing a liquid biopsy might teach us which drug to use. Our review didn’t just look at the evidence for using tumor cells – exosomes and circulating tumor nucleic acids have promise, too. I think there are a variety of very positive outcomes that could be seen from the use of liquid biopsy in the coming years.

Are further studies needed?

Absolutely! But we already know the technique works – liquid biopsy should already be regularly used in metastatic breast, colon and prostate cancer cases to help judge the relative severity of the disease, but that simply isn’t happening in most cases. I believe this method would empower pathologists to look at the genetic information found in these cells, and this could trigger research to help us further understand this technology and its applications. Our goal needs to be to further evaluate liquid biopsies and their uses in particular cancers, with the aim of providing precision medicine.