Targeted drug gene testing can be done with 2 types of specimens: 1. The best is histological specimen, that is, using tumor tissue as the specimen, which has the highest accuracy and positivity rate for gene testing and is the preferred clinical test method. 2. If there is really no histological specimen, using liquid biopsy or circulating tumor cell DNA method is also possible. The positive rate of this test is 60%-70% and the accuracy rate is about 80%-90%. If there is no way to obtain tissue specimens or patients are not willing to do tissue specimen biopsy, they can choose the 2nd method to do genetic testing, which can be done for lung cancer, colorectal cancer and breast cancer.