Circulating biomarkers can derive from various molecular origins, including small molecules such as glucose or cholesterol, DNAs (i.e., specific mutation, translocation, amplification in characteristic genes such as BCRA1, KRAS, cell-free DNAs, RNAs (mRNAs and miRNAs), proteins (i.e., hormones, antibodies, oncogenes, or tumor suppressors), exosomes and tumor cells. Here, KRAS is linked to neoplasm.