DNA screening is genetic screening. Genes are segments of DNA molecules that carry genetic information and can be monitored by blood, body fluids and tissues for susceptibility genes to determine the presence of disease-causing mutations, thus predicting an individual’s risk of developing a certain disease. The role of tumor gene screening is as follows: 1) prediction, through gene screening, the risk of certain tumors or diseases can be predicted; 2) confirmation, through gene screening, the risk of which disease can be determined; 3) gene screening is needed before targeted drug therapy to determine whether targeted therapy is needed. 2. People who are suitable for genetic screening are as follows: 1. people with family history, meaning immediate or collateral relatives with certain tumors; 2. relatives who had cancer when they were very young; 3. although they are distant relatives, they have very specific rare cancer, which is related to mutation of certain genes; 4. people with diseases related to hereditary cancer, such as polyps; 5. people among relatives who received genetic screening and who are found to have a genetic mutation. For now, genetic screening is not a diagnosis of the disease, but only a genetic screening to assess the risk of developing cancer and to predict and warn people at risk.