That’s finally changing. One of the newest developments in cancer detection and monitoring is something called a liquid biopsy. It’s a test that can detect tumor DNA circulating in the blood. I think it’s the most exciting thing I’ve seen since I started my career. A tissue biopsy has always had its limits—it’s painful, and sometimes when a doctor takes a sample, they miss the spot where the cancer is. Our hope is that we’ll soon be able to use blood samples to detect cancer earlier than ever before.

Of course before we can even roll out reliable liquid biopsy tests, we’ll need to build and clinically validate a library of circulating tumor DNA—the genetic fragments that can be detected with a blood test. My company, Illumina, is still in the research phase of building that library: Sampling solid tumors and matched blood specimens and sequencing both the cellular DNA and the blood fragment DNA. We’re looking at how detection of various mutations within circulating DNA fragments correlates to certain cancers. Many more clinical trials need to be done and millions of dollars still need to be invested. But eventually, we’ll begin to match specific clinical outcomes, such as therapy response, with the circulating DNA that is sequenced. We’re also working on building databases that will show which cancer drugs work most effectively with which cancers at a genetic level. We’re moving forward with this research at an exciting pace; in the next five to ten years, it’s going to make a tremendous difference in how we practice medicine.