What is K-ras gene? K-ras gene is the determinant of signal transduction protein and plays an important role in this transduction pathway, thus affecting the growth and spread of tumor. Wu Bin, Department of Basic Surgery, Peking Union Medical College Hospital 1.Why is K-ras gene testing important? What are the benefits of genetic testing for me? The gene can be normal (called wild type) or abnormal (mutant). k-ras mutant encodes abnormal protein, which stimulates the growth and spread of malignant tumor cells; and it is not affected by the upstream EGFR signal, so it has poor effect on anti-EGFR treatment. Genetic testing can not only provide insight into oncogenes, but more importantly, screen out colorectal cancer patients who are effective against anti-EGFR targeted therapies, helping doctors to select the most effective treatment for tumor patients, thus truly individualizing treatment for tumor patients, and also significantly reducing related treatment costs and toxic side effects. Currently, K-ras status is routinely tested before medical treatment for colorectal cancer patients in Europe and the United States. 2. Do patients who have just had their primary colorectal cancer lesions removed need to be tested for K-ras gene? The early detection of K-ras can provide timely information about the status of the gene, so as to understand the patient’s risk of recurrence and metastasis and prepare for the best treatment in the future. Please keep this point in mind: the earlier the K-ras test for colorectal cancer patients, the better. 3.When does the K-ras gene mutation occur? The gene mutation occurs at the early stage of tumor malignancy and the K-ras gene in the primary and metastatic foci are highly consistent. It is generally believed that the K-ras gene status will not change due to treatment. 4.The probability of K-ras gene abnormalities in colorectal cancer patients? The rate of K-ras mutation in colorectal cancer patients is 30%-35%. 5.Is K-ras gene testing complicated? What kind of standard is required? Genetic testing is simple and easy to perform, and most of the regular hospitals in China can perform the test, and the traditional PCR (polymerase chain reaction) plus DNA sequencing method is commonly used in China. Specimen requirements: Fresh surgical specimens can be stored in formalin and sent to the testing center. Those who can borrow pathology wax blocks can send the specimens directly to the testing center. If you cannot borrow pathology specimens, you can ask the pathology department to cut 5-10 white slices with a thickness of 5-10 um (microns) and send them to the testing center in EP tubes. Please consult the testing center for specific requirements. 6.K-ras gene test price and time? The genetic test usually ranges from 500 RMB to 900 RMB (slightly different according to the price approved by the local price), and the report is usually issued in 5 to 7 days (not more than 1 week). 7.Is EGFR (epidermal growth factor receptor) treatment also suitable if I have colorectal cancer and liver metastasis is also found? The benefits of receiving anti-EGFR (epidermal growth factor receptor) therapy for colorectal cancer combined with liver metastases: the rate of complete resection of liver metastases is significantly increased, especially those with normal K-ras gene gain more benefits and prolong life. Therefore, patients with liver metastases from colorectal cancer should also be tested for the K-ras gene.