Detection of fragments of circulating tumor DNA (ctDNA) in the bloodstream for diagnosing the presence or recurrence of cancer is growing in interest in healthcare research. The ctDNA shed from a tumor can now be detected reliably in the clinical laboratory by locating certain genes which are methylated in colorectal cancer (CRC) cells but typically are not methylated in normal blood cells. With approximately 50,000 deaths each year, CRC is among the leading causes of cancer-related mortality in the United States. Although highly treatable when detected early, only 25-50% of CRCs are caught when a cure is very likely. Current monitoring tools, however, are either highly expensive for routine care or lack adequate sensitivity to reliably detect disease. The recommended blood test for recurrence monitoring—carcinogenic embryonic antigen (CEA)—has significant limitations, with many false negative and false positive tests. A new test has been developed for recurrence monitoring, Colvera (Clinical Genomics), that measures the presence of methylation in two well-characterized genes associated with CRC development ( and ). In initial clinical studies, Colvera detected twice as many recurrent CRC cases as CEA and also compared well with FIT in a larger screening cohort. Although it is not yet clear if earlier detection results in reduced mortality, further studies are planned to determine if the new test can improve early detection of metastatic CRC and improve outcomes for these patients.