The difference in KRAS mutational status between the two body sources might be due, as previously reported for other nonblood biological fluids [32], to a more direct contact of DF with tumors, which determines a greater proportion of ctDNA than plasma, where the concentration of target DNA is often very limited and depends on several factors, or to the potential of proximal body fluid to enable the characterization of a genetically distinct population of tumor cells more reflective of the primary tumor. Here, KRAS is linked to neoplasm.