KRAS and colorectal carcinoma: Interestingly, serial monitoring of patients' plasma cell-free DNA (cfDNA) identified that rebounds in BRAFV600E levels coincided with disease progression, as well as the emergence of adaptive resistance mechanisms such as mutant KRAS, which indicates cfDNA monitoring may correlate with patient response and influence combative therapy prescription, more so than CEA levels which is the typical clinical CRC marker.