The incidence of malignant tumors is at a low level from 0 to 39 years old, and increases rapidly after 40 years old, and reaches a peak after 80 years old. So, which groups of people need to undergo early cancer screening? According to epidemiological survey, the following high-risk groups need early cancer screening: first, people who smoke more; second, people with family history of tumor; third, people who have a history of tumor; fourth, people with special types of work, such as long-term exposure to carcinogenic substances such as arsenic, chromium, asbestos, nickel and cigarette smoke; fifth, people with long-term chronic infectious diseases.