KRAS and neoplasm: Cell-free DNA (cfDNA)—particularly its tumor-derived fraction, circulating tumor DNA (ctDNA)—offers complementary information: mutant KRAS ctDNA in plasma has been associated with higher recurrence risk and shorter recurrence-free survival in surgical series (Ako et al., 2021) and ctDNA kinetics may report minimal residual disease more sensitively than imaging (Bartolomucci et al., 2025).