Cancer is currently an incurable disease and people are afraid of talking about it, but the incidence rate of cancer is gradually increasing, with more than 4 million new cancer cases and 3.5 million deaths in China every year, which is equivalent to 6 people diagnosed with cancer every minute. The incidence of cancer is caused by a combination of internal and external factors. The internal factor is the congenital genetic condition, while the external factor is the acquired living environment, habits and diet structure. For example, if people in a factory eat the same food and drink the same water source, the reason why each person has different diseases over the decades is because of the different genes of individuals. Just like some people smoke until they are 80 or 90 years old, some husbands smoke and their wives suffer from lung cancer instead of second-hand smoke. How can we know the genetic condition of an individual to prevent it? Today, genetic testing is widely available in developed countries such as the United States, Japan and Europe, and the mortality rate of cancer in the United States has dropped by 25% in the past two decades. Cancer is caused by a combination of genetic mutations in the genes, the environment and lifestyle habits, and the loss of immune control of cells. For example, if you are detected to be at high risk of lung cancer, you should first quit smoking, stay away from second-hand smoke and kitchen fumes, use air purifiers, protect yourself from haze, and eat more lung moistening foods to reduce the probability of gene mutation. In addition, regular medical checkups can be conducted for this purpose, such as regular lung cancer tumor indicators and chest CT to detect abnormalities in time and early detection is the key to cancer treatment. When the diagnosis of diseases is improved to the level of genetic diagnosis, it is the progress of medicine and also provides a good guarantee for people’s health protection.