Primary Care and Early Cancer Diagnosis – The Role of Liquid Biopsy

March 6, 2017

By Florin Selaru

Early Cancer Diagnosis with a Blood Draw In Your Primary Care Doctor’s Office?

Early cancer diagnosis in a primary care setting is a timely topic. Patients tend to see their primary care doctor at least once a year. Methodologies and techniques that would allow early cancer diagnosis in a primary care setting are emerging. Among them, liquid biopsy (blood test that allows cancer diagnosis) appears closest to clinical practice. The hypothesis behind using a blood test to diagnose cancer is simple. Cancers release their mutated DNA into circulation. If one knows how to look and what techniques to use, then it would be possible to diagnose cancer with a blood draw. In addition, you could diagnose cancer before it caused symptoms. This hypothesis is now getting closer and closer to becoming reality. So, how long until we are ready to screen for cancers with a simple blood draw done in the primary care doctor’s office?

Some History

We are still in the early days. But how did we get here? First, it started with the realization – put forth by Dr. Vogelstein at Johns Hopkins – that cancer is a genetic disease. In other words, it makes sense to look at genes, or DNA, to diagnose cancer. Second, it was not too long ago when the cost for 1 human genome was $100M. Today, it costs less than $1,000. Third, it was the realization that cancers shed off circulating tumor DNA (ctDNA) in the blood stream. The development of technologies to identify ctDNA and interpret this information was the next step.

Looking Forward

What is next? Are we ready to offer liquid biopsies to diagnose cancers? It would be simple – go to your primary care doctor, have a few vials of blood drawn, and get the results in days. Well, we are not there next. There are many questions to answer. How sensitive are these tests for each cancer? Can we identify early cancers (in addition to late cancers)? How do these new diagnostics compare versus the gold standard? These questions are not easy (nor inexpensive) to answer. The good news is that the massive funding is going towards further development. Grail, a company that aims squarely at answering these questions, has just raised $900M to develop further their tests.

There is reason to hope that in the not too distant future, we will be able to screen for cancers at the annual physical exam.

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