According to the U.S. National Comprehensive Cancer Network (NCCN) guidelines from November 2008 (http://www.nccn.org/about/news/newsinfo.asp?NewsID=194) and recommendations of the American Society of Clinical Oncology (ASCO)[8], screening of the status of the KRAS gene is mandatory when deciding whether or not a patient with colorectal cancer should receive anti-EGFR drugs. Here, KRAS is linked to colorectal cancer.