Liquid biopsies and circulating tumor DNA are changing and improving the way cancer is detected and treated. In this episode, Sameek Roychowdhury, PhD, MD, explains the basics of circulating tumor DNA, how it’s being used at the James, his lab’s clinical trials, and the promising future. “When a normal cell and a cancer die they sheds fragments of their DNA,” he said. “Cancer can be detected in the blood by looking for these fragments and this is becoming an important research tool and treatment tool for the care of cancer patients.” For example, about 50 percent of cancer patients who have a tumor surgically removed will have a recurrence. And it’s very difficult to determine which patients will have the recurrence. Minimally invasive liquid biopsies after surgery “helps us stratify and determine patients with a lesser recurrence risk who won’t need chemotherapy or immunotherapy treatment versus those patients who need even more treatment than we’ve normally given them in the past.” Monitoring circulating tumor DNA “also becomes part of the surveillance program and we’ll do a precise test every three months that measures fragments in the blood,” Roychowdhury said, adding that finding a recurrence of cancer from these fragments, months before it would appear on more traditional scans “allows us to make a diagnosis about the molecular drivers of the cancer and we can begin treatment earlier and better understand which treatment options will work best.”