The NRAS mutation is found in several cancers such as melanoma (13 ~ 25%), colorectal cancer (1 ~ 6%), lung cancer (1%), thyroid cancer (7%) and hepatocellular carcinoma (10%). It is known that the response to colorectal cancer drug such as Erbitux and Cetuximab decreased and the prognosis of the patient with metastatic colorectal cancer is poor if the patient has NRAS mutation. Recently, there are some articles reporting that responses to drugs may be different for NRAS mutation type, so it is important to genotype each mutation. Genotyping test for the NRAS gene mutation is necessary especially for predicting drug sensitivity and prognosis. This test is expected to play an important role in predicting the treatment and prognosis of patients.