Since 2016, the National Comprehensive Cancer Network (NCCN) guidelines have recommended genotyping for KRAS mutations in tumor tissues for all patients with suspected or confirmed metastatic colorectal cancer, and that patients with KRAS mutations should not be treated with either cetuximab or panitumumab, either alone or in combination with other anticancer agents.4, 8. The gene discussed is KRAS; the disease is metastatic colorectal cancer.