NRAS and colorectal carcinoma: Mutations in the KRAS and NRAS genes occur in approximately 40% of metastatic CRC (mCRC) samples.1 Patients with metastatic CRC and KRAS mutations have the poorest prognosis.2,3 However, two NGS studies found no outcome difference between KRAS mutations and KRAS / NRAS/ BRAF genotype mutations.4,5 Studies consistently show KRAS wild-type CRC tumors are associated with better survival than mutant KRAS tumors.6-9