KRAS and neoplasm: Some data suggest that the amount of mutant DNA correlates with tumor burden and can be used to identify the emergence of resistant mutations.[9-14] The concept of mutation testing from urine cfDNA has been assessed in a pilot study in patients with advanced colorectal cancer and other colorectal diseases in which KRAS mutations in urine cfDNA were concordant in 95% of cases with KRAS mutation status in tumor tissue.[15] We examine in our study whether urine and plasma cfDNA can be used as an alternative to tissue biopsies for BRAF V600E mutation testing in patients with ECD.