Genetic testing for targeted drugs is an important test before using targeted drugs, and genetic testing must be done before using targeted drugs. Take lung cancer as an example, if you use targeted drug gefitinib, erlotinib or third generation oxitinib, you must do genetic testing before lung cancer treatment to determine if it is combined with EGFR gene mutation. Without this gene mutation, the use of targeted drugs has no effect, while with the above gene mutation, the use of targeted drugs can achieve an efficiency of about 70%. If you have ALK mutation, you can use crizotinib, alectinib or cretinib, which are targeted drugs for ALK mutation. Breast cancer and rectal cancer can also be treated with targeted drugs, and genetic testing should be done before using targeted drugs.