The three levels of cancer prevention are different prevention methods for different groups of people and different stages, as follows: 1. Primary prevention is to provide health education for all people, so that people can generally understand the risk of cancer, develop good living habits and reduce the intake of bad food; 2. Secondary prevention is the three early stages, early detection, early diagnosis and early treatment. In addition to routine medical checkups, it is important to pay attention to special changes in the body on a daily basis, and to take the initiative to contact doctors when encountering problems, and not to deal with them blindly on your own; 3. Tertiary prevention is a means for cancer patients to prevent recurrence, and to take medical measures to improve the tumor physique and reduce the risk of cancer under the guidance of a specialist and according to the risk factors of that cancer.