When cancer is suspected, doctors often remove samples of the suspicious tissue via surgery or needles. The samples can then be examined to determine if they are cancerous or not. In addition to being invasive, the samples taken may miss cancerous areas, leading to an incorrect result.
Liquid biopsies are poised to change the way many cancers are detected. The tests rely on detecting indicators (markers) of cancer that can be found in small samples of blood. The markers can be cancer cells themselves, or products produced by cancer cells. The tests should be more accurate, and definitely less risky than regular biopsies.