Circulating tumor DNA (ctDNA), also known as cell-free tumor DNA, is genetic material that's freely floating in the bloodstream of cancer patients. The source of ctDNA is the tumor, where dead tumor cells break open and release the tumor DNA into the patient's blood. ctDNA represents a non-invasive cancer biomarker that can indicate the presence of disease. And because detection requires only a blood sample, the technique of using ctDNA for cancer diagnosis is often called "liquid biopsy."
One of the biggest advantages to liquid biopsies is early detection. Because tumor DNA can be picked up in blood, patients can potentially be treated before a tumor grows. This method also allows doctors to better monitor patients for cancer progression and recurrence. In all cases, the early detection gives doctors more time to form better treatment plans for their patients.