Cancer metastasis causes 90% of all cancer-related deaths. Scientists agree that the metastases occur when cancer cells are shed from the primary tumor, carried by the peripheral blood, and deposited at a distal site to create a new colony. An ability to etect circulating tumor cells (CTCs) or cell-free cancer DNA (cfDNA) in blood or saliva opens possibilities to suspect cancer even before it is visible on radiological images.Minimally invasive bodily fluid testing—dubbed liquid biopsies—allows for frequent testing for residual disease or cancer recurrence, and could be uniquely beneficial when cancer develops in sites inaccessible to surgical biopsies. But what is the best technology to capture and detect cancer material in liquid biopsies? Multiple creative approaches are currently being tested, jostling to reach the clinical diagnostic market.