NRAS and colorectal carcinoma: We did not find any sequence variant in BRAF or NRAS genes, reported to be mutated in cfDNA from CRC patients at a frequency ranging from 5 to 10% and from 3 to 8%, respectively.6 The great variability of driver genes mutation rates in cfDNA reported in previous studies may be due to the different pre-analytical and analytical settings affecting the results.